I think you have over-simplified it. But your point is correct.

Here is another way of looking at the relationship:

Assume you are the only one person working on a task, let’s call it Task A. Task A is made up of parts, let’s call them Parts 1, 2 and 3. Part 1 is the essential guts of the task, and parts 2 and 3 are things that are just the finishing touches or non-essential to the business of Task A.

If you know it will take 2 hours to complete parts 1 and 2, but someone comes along and says you only have 1 hour to complete the task. You cannot do both parts 1 and 2 of the task because the time has compressed.

Likewise, if you are given 3 hours to complete the task, and you know it will take 2 hours to do parts 1 and 2, and 1/2 hour to do part 3, you now have time to do all three tasks.

The expansion part is pretty intuitive — the more time you have, the more you can add.

What I find in the compression area, though, is that far too many people think that compressing the time has no effect on how much can be accomplished.

I have seen far too many managers say, “You need three hours to get parts 1, 2 and 3 done? Do it in 0.5 hours.” and then not understand this is not possible.

The point of the article is that when resources are fixed, time and amount accomplished are related.