When task constraints work best

If you make work a scarcer quantity, you’re more likely to use time wisely and get things done than if it feels like an endless to-do list.

And you cand do this by restricting your hours or restricting your workload.

• Restricting hours: set aside a certain chunk of time for work and don’t work outside of it. For example, the Pomodoro technique for working in short bursts of time.
• Restricting workload: instead of deciding on a set number of hours, you decide on a set number of tasks. 

The biggest advantage of constraining time is that it’s always unambiguous. If you decide to work for three hours and then stop, there’s no confusion there.

Disadvantage: time constraints can encourage a sloppier attitude towards work. For example, you might decide to spend all day studying in the library—but without tasks to constrain your productivity, you end up checking your phone.

• It’s unclear the time and effort required to complete the task.
• The work itself is ambiguous and may require a lot of trial-and-error.
• The work is continuous and can’t be easily divided into discrete chunks.

The advantage of constraining tasks is that it focuses directly on the object of productivity: whatever you’re trying to accomplish: you can't fool yourself into believing you’re working hard but you’re not actually accomplishing much.

Disadvantage: tasks can often be ambiguous or hard to predict. If you fail to predict properly you might create to-do lists that are unachievable or those that are trivial.

• Tasks are discrete and fairly predictable.
• You might be tempted to fill up time without making real progress
• The tasks are frequently repeated, and therefore easier to estimate.