The version of this quote I've heard the most is "The last 10% of a project takes 90% of the time." It's a bit different, but the idea is the same: the real wor

The version of this quote I've heard the most is "The last 10% of a project takes 90% of the time." It's a bit different, but the idea is the same: the real work of implementing a feature comes in handling unexpected behavior and edge cases. It can look finished from the outside, but imagining and preparing for every conceivable outcome takes much of the time.