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A quote waiting for the director’s signature, an invoice stuck for lack of approval, a single person who knows how to configure the software: every company has its bottleneck, the step where work arrives faster than it leaves. It sets the pace for everything else, and it is often a person, not a machine. This article from our section on process automation and business bots explains how to find it, why speeding up the other steps achieves nothing, and how automation clears it without taking the decision away from those who must make it.
In short
The bottleneck is the slowest step in a flow: it determines the flow’s throughput.
You spot it by what is waiting in front of it, not by how busy it looks: a growing pile, chasers, “where is my file?”.
Speeding up another step only lengthens the queue in front of it.
You free it by removing everything that does not need its judgement, then by giving it resources: a delegation threshold, a second person, an automation.
What is a bottleneck in a business?
Definition
Bottleneck
The step in a flow with the lowest capacity: work arrives there faster than it can be processed, and a queue forms in front of it.
Like the neck of a bottle, the bottleneck decides the throughput: however wide the rest is, nothing comes out faster than what it lets through. Israeli physicist Eliyahu Goldratt made it the centre of his theory of constraints, popularised in 1984 by his business novel The Goal. One of his rules sums up what is at stake:
An hour lost at the bottleneck is an hour lost for the entire system.
The phenomenon even has its own formula. Little’s Law, proved in 1961 by the American researcher John Little, states that the average number of items in a system equals their arrival rate multiplied by the time each one spends in it. Read the other way round, it says the essential thing: at equal throughput, the more files are waiting, the longer each one takes to come out.
Why are bottlenecks so often people?
In a factory, the bottleneck is often a machine. In a service business, it is often a person, for reasons that add up.
Centralised approval. A manager who signs every quote, every purchase, every discount: their day becomes the capacity of the whole flow. Supplier payments show this well. According to APQC, an American benchmarking organisation, nothing slows down invoice processing as much as an approval still to be obtained, when the accounts team has to chase management’s sign-off above a certain amount. The gap between companies is clear:
or less to receive, process, approve an invoice and schedule its payment, in the fastest quarter
or more for the same tasks in the slowest quarter
Concentrated knowledge. Only one person knows how to price a complex project, configure the software or answer a long-standing customer. When they are away, everything waits.
Constant interruption. The bottleneck person is also the one people call on most, and each request costs them dearly. Researcher Gloria Mark, of the University of California, Irvine, observed that interrupted employees return to their task the same day in 81.9% of cases, but on average 23 minutes and 15 seconds later, after going through about two other tasks. In the lab, her team also showed that interrupted people compensate by working faster, with no loss of quality, but at the price of more stress and frustration.
How do you spot a bottleneck?
You do not spot a bottleneck by how busy things look: the step that rushes around most is not necessarily the slowest. You spot it by what is waiting in front of it. The diagram follows a purchasing flow in which management approves every expense; the “As a system” view shows what a dashboard sees.
A purchasing flow, and its approval bottleneck
Every step is handled by a person. Information waits in inboxes, and nobody sees where it piles up.
- Business teams
- A person: Records each purchase request
- Procurement
- A person: Compares the quotes received
- A person: Prepares the purchase order
- Management
- A person: Approves every purchase
- Accounting
- A person: Reads the supplier invoice
- A person: Checks discrepancies
- A person: Schedules the payment
Automations relay the information, people keep the decisions, and the dashboard shows where work is waiting.
- Business teams
- An automation without AI: Records each purchase request
- Procurement
- An AI: Compares the quotes received
- An automation without AI: Prepares the purchase order
- Management
- A person: Approves every purchaseBottleneck
- Accounting
- An AI: Reads the supplier invoice
- A person: Checks discrepancies
- An automation without AI: Schedules the payment
- A person
- An automation without AI
- An AI
- A piece of information
- A queue
The automations around management move fast, and that is exactly why the queue becomes visible: it forms in front of the only step whose pace has not changed. Without a dashboard, a few signs still give a bottleneck away:
- a pile that grows in front of the same step, week after week;
- chasers and “where is my file?” converging on the same person;
- files spending more time waiting than being worked on;
- one person’s holidays slowing down the whole flow.
The most reliable method is still to measure the waiting time in front of each step. It is the indicator our guide Dashboards and KPIs: defining them with leadership puts first.
How do you free a bottleneck?
Goldratt proposed five steps, which the TOC Institute summarises and which apply as they are to an office flow:
- Identify.
Find the step in front of which files wait longest.
- Exploit.
Leave the bottleneck only what needs its judgement: the file reaches it complete, checked and summarised, and it no longer wastes time hunting for a document.
- Subordinate.
Set the rest of the flow to its pace: there is no point preparing more files than it can handle.
- Elevate.
Give it resources: a threshold below which approval becomes automatic, a second trained person, an automation.
- Repeat.
Once this bottleneck is cleared, another appears elsewhere: start again from the top, without letting old habits become the new constraint.
The order matters. Hiring or buying a tool belongs to the fourth step: before getting there, the two previous steps often free up enough capacity to do without.
What can automation do for a bottleneck?
Automation does not replace the decision; it removes everything around it. In practice, on an approval step:
- preparing the file: rules gather the documents (the quote, the remaining budget, the supplier’s history), and an AI summarises a long file in a few lines, flagging anything out of the ordinary;
- delegating by threshold: below an amount and within a budget set by management, approval becomes automatic, and it is logged;
- batching requests: a summary at a fixed time replaces requests as they come in;
- making the status visible: when everyone can see where their file stands, the “where is my request?” messages stop interrupting the bottleneck person.
Most of these actions are simple rules, without AI; our guide Automation without AI: when a rule is enough helps you spot the steps where a model is really justified.
It is the split of roles we apply to customer support, where AI sorts requests and humans review: the person’s time goes to what needs their judgement, not to handling.
Watch out
Speeding up elsewhere achieves nothing
Automating a step that is not the bottleneck feels like progress, but it only sends work faster into the queue: the end-to-end lead time does not move, and the pile grows. For Goldratt, an hour saved at a non-bottleneck is a mirage. Measure first, automate second.
From the field
An approval we want, but visible
On Palmora Property, a property portal we run, each newly imported listing waits for human approval before going live: that step is what stops a mistake reaching the site. So that it does not become an invisible bottleneck, the report the team receives every morning shows the approval queue, next to the new properties and the synchronisation status.
Where to start?
Take the flow whose delays cost you the most, and ask the people working in it where files wait. Then measure those waits for a few weeks: the bottleneck shows up quickly, and it is not always the one you expected. Our article Running your company as a system, not in reaction puts this approach in the context of the whole organisation.
Our digital and AI maturity audit does this work with you: a map of your processes as they really run, and projects ranked by impact, in two to four weeks. Once the bottleneck is identified, our automation offer prepares its files and removes the retyping around it, using AI only at the steps where a rule is not enough.
Frequently asked questions
How do I find where my company’s bottleneck is?
Look at where files wait, not where people rush. The bottleneck is the step in front of which work piles up and towards which chasers converge. To be sure, measure for a few weeks the waiting time before each step of a flow: the step where it is longest is your bottleneck. A single person whose holidays slow down the whole flow is another sign.
Is the bottleneck always a person?
No. It can be an overloaded tool, a slow supplier, a rule that is too strict or a budget that forces everything to be approved. In a service business, though, it is often a person: the one who approves, the one who knows, or the one who gets interrupted most. The method is the same in every case: remove what does not need their involvement, then give them resources.
Does hiring fix a bottleneck?
Sometimes, but it is the most expensive and slowest solution, and it comes last. Before recruiting, take away from the bottleneck everything that does not need its judgement: gathering documents, chasing, retyping. Set delegation thresholds and batch requests. These measures often free up enough capacity, and if they are not enough, the new hire arrives in a flow that has already been clarified.
Should you remove approvals to go faster?
No, you should put them in the right place. An approval that protects the company, such as a large purchase or a publication, keeps its purpose. Those that never change the decision can become automatic below a threshold set by management, with a record of each pass. The flow gains speed without losing control, and the approver keeps their attention for the real cases.
What if the bottleneck is the manager?
It is common in companies that grew quickly around their founder. The first step is to make the queue visible: how many files are waiting for their decision, and since when. Then come delegation thresholds, files prepared and summarised, and a fixed slot for deciding. The manager keeps the decisions that commit the company, and stops being the mandatory passage for everything else.
Sources
- John Little, Little’s Law as Viewed on Its 50th Anniversary, 2011 (new tab)projectproduction.org
- Perry D. Wiggins, CFO.com, based on APQC data, August 2022 (new tab)cfo.com
- Gloria Mark interviewed by the Gallup Business Journal, June 2006 (new tab)news.gallup.com
- Mark, Gudith and Klocke, The Cost of Interrupted Work, CHI 2008 (new tab)dl.acm.org
- TOC Institute, The Five Focusing Steps (new tab)tocinstitute.org
- IEEE, Optimized Production Technology (new tab)technav.ieee.org
John Little, Little’s Law as Viewed on Its 50th Anniversary, 2011
Read on projectproduction.org(new tab)Gloria Mark interviewed by the Gallup Business Journal, June 2006
Read on news.gallup.com(new tab)Jim · founder of Brain Plus AI
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