Does the 80/20 rule of time management apply to developers? [closed]

Question

Jeff's recent article linked to a time management example of the First Fit Decreasing algorithm, which talked about the Pareto principle (or, the 80/20 rule) of time management, that is, that 80% of the work we produce in 20% of our time.

Now we've all heard the programmer quote:

The first 90% of the code accounts for the first 90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time.

But all jokes aside, it is often as if 20% of your code is to do what you want, and the other 80% is to handle exceptions... so does the 80/20 rule really apply to developers?

Does anyone have any examples of why it does / does not apply to us?

Answer 1

I think Hofstadter's Law applies.

It always takes longer than you expect, even when you take Hofstadter's Law into account.

--Douglas Hofstadter

On a more serious note, take a look at Critical Chain Project Management. It recommends that you give two estimates for each step in your project. One is an optimistic estimate that you're about 50% sure you can meet if everything goes right. The other is a more realistic estimate that takes lost time and mistakes into account (my paraphrasing, don't blame the author). Over time and several projects you'll learn which estimate is more accurate, and by how much. It varies by developer, so you need to keep track.