When I first started out in engineering, people would talk disparagingly about somebody being a "ninety-five percent" guy. I had one for a boss. He would assign you a partially complete task saying it was ninety-five percent complete. You just had to do the five percent that took ninety-five percent of the time.

In Agile development, a task or story gets no credit until it's completely done. This is an important concept. Done is often a lot farther than it looks. A developer may write a bit of code that compiles and seems to work. He may think he's done, but he's not done-done. The team needs do develop a working agreement of what done-done means.

Here are some articles on the topic: