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The Lever #021: The Stock-Sanford Corollary: Counterintuitive advice for getting things done

Last week we looked at how work expands to fill time available.

Today I'll flip that idea upside down.


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Why is it that even when you have a lot of time to do a job, sometimes you still leave it until the last minute?

And why is it that, sometimes, that's when you do your best work?

In a previous issue you learned about Parkinson's Law, and how work expands to fill time available. Give yourself a lot of time and you do more unnecessary tasks (or just do the work slower!) until you've taken up all the time.

So what happens to work when the time available is reduced?

That's where this corollary comes in:

"Work contracts to fit the time we have available for its completion."

- Stock and Sanford

The Stock-Sanford corollary builds from Parkinson's Law, which states that work expands to fill the time available for its completion. (A corollary is a statement or proposition that builds from a previously established principle.)

Named after its creators, Lancelot Hogben Stock and W. Roy Sanford, the corollary states that work contracts to fit the time we have available for its completion. In other words, if you set a shorter deadline for ourselves, you will work more efficiently and get the same amount of work done in less time.

The corollary was first introduced in the 1932 book "Industrial Efficiency and State Intervention", which was a critique of the British government's efforts to increase industrial efficiency, and the corollary was presented as a counterargument to the prevailing view that longer working hours would increase productivity.

Stock, a mathematician and geneticist, and Sanford, an economist, both worked at the London School of Economics at the time. They developed the corollary based on their observations of workers in various industries, including the factory workers who were the subject of their book.

The thesis was simple: by setting shorter deadlines for workers, managers could increase productivity by creating a sense of urgency and reducing the amount of time wasted on non-essential tasks. If workers had less time to complete a task, they would be more focused and efficient in their work.

The corollary was a radical idea at the time, as it went against the prevailing wisdom that longer working hours were necessary for increased productivity. While not an immediate success, it eventually gained acceptance as a valuable tool for increasing productivity. In the decades that followed, it was adopted by business leaders and productivity experts around the world, and it has since become a staple of productivity literature.

Battle of the Big Ideas

Parkinson's Law and the Stock-Sanford Corollary are both productivity principles that deal with the relationship between time and productivity. However, while Parkinson's Law states that work expands to fill the time available for its completion, the Stock-Sanford Corollary proposes that work contracts to fit the time available for its completion.

The main difference lies in their approach to time management. Parkinson's Law suggests that setting longer deadlines can lead to decreased productivity and efficiency, as it allows for more time to be spent on non-essential tasks. In contrast, the Stock-Sanford Corollary proposes that setting shorter deadlines can increase productivity by creating a sense of urgency and forcing individuals to prioritize tasks and avoid distractions.

Another key difference between the two principles is their focus. Parkinson's Law is primarily concerned with the negative effects of time on productivity, while the Stock-Sanford Corollary emphasizes the positive effects of time pressure on motivation and efficiency.

While both Parkinson's Law and the Stock-Sanford Corollary deal with the relationship between time and productivity, they take different approaches and have different implications for time management and productivity.

Why Does it Work?

The Stock-Sanford corollary follows the psychological principle of "time pressure," which is the sense of urgency that individuals feel when they are faced with a deadline.

Studies show that time pressure can have both positive and negative effects on performance. It can increase motivation, focus, and efficiency by forcing individuals to prioritize tasks and avoid distractions. But it can also lead to stress, anxiety, and a decrease in the quality of work.

One study found that time pressure increased the speed and efficiency of workers in a data entry task, but also led to more errors and a lower level of accuracy overall (Jex et al., 2001). Another study found that time pressure had a positive effect on the creativity of participants in a brainstorming task, but only up to a certain point; beyond a certain level of pressure, creativity decreased (Amabile et al., 2002).

In addition to psychological research, there is also evidence from the field of operations management that supports the use of the Stock-Sanford corollary. The concept of "lean manufacturing," for example, which emphasizes the elimination of waste and the optimization of workflow, has been shown to be effective in increasing productivity and reducing costs in numerous industries (Womack et al., 1990).

The science behind the corollary is complex and requires a deep understanding of human psychology, operations management, and productivity research. While it can be effective in improving productivity, it is important to take into account the potential negative effects of time pressure on performance.

Knowing that, it stands to reason that every task then has an optimum amount of time to complete, that yields the highest reasonable level of quality.

How can you find that intersection for yourself?


To use the principles of the Stock-Sanford corollary to your advantage, follow this 3-step method:

1. Set realistic and achievable deadlines for tasks and projects. This means breaking down larger projects into smaller, more manageable tasks, and setting deadlines for each of these tasks that are shorter than the overall project deadline.

2. Prioritize tasks based on their importance and urgency, and to eliminate or delegate tasks that are not essential. This can help reduce feelings of overwhelm and increase focus and efficiency.

3. Do the work using productivity techniques such as time blocking and task batching. These techniques can help to increase focus and eliminate distractions, allowing you to get more done in less time.

Finally, by recording the amount of time it takes you to actually complete a task you will begin to develop an acute sense of how long things actually take. Over time this will allow you to better plan your work, without spending more time than needed.

For every task you will find there is a point of diminishing return on quality for time invested. The smart move then is to identify this inflection point and tailor your time on task to match that.

Use Wisely

The Stock-Sanford corollary provides a powerful framework for increasing productivity and achieving greater success in work and life. By understanding its principles you can achieve greater efficiency, reduce stress and overwhelm, and achieve your goals with greater ease in less time.

But it is not a one-size-fits-all solution. While it can be effective in increasing motivation and efficiency, it can also have negative effects if not used properly. Be sure to find the right balance between time pressure and workload, and to ensure that deadlines are realistic and achievable.


Amabile, T. M., Hadley, C. N., & Kramer, S. J. (2002). Creativity under the gun. Harvard Business Review, 80(8), 52-61.

Jex, S. M., Elacqua, T. C., & Kirsh, H. (2001). Time pressure effects on skill acquisition and performance. Journal of Occupational Health Psychology, 6(4), 256–271.

Womack, J. P., Jones, D. T., & Roos, D. (1990). The machine that changed the world. Scribner.


Bonus: ProductivityGPT Prompt

I needed a chart to demonstrate the idea in this weeks issue. The above chart was made in ChatGPT v.3.5 in less than 2 minutes.

Here's how:


Create a table that compares time on task and quality. Quality should increase from 0 to 10 but not in a linear fashion. Demonstrate the point of diminishing returns, after which time on task results in smaller quality gains.


A quick and easy prompt for chart generation.


When you are ready, here are a few ways I can help:

1. Subscribe to The Lever (if you haven't already)

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