Most interviews seem to weigh heavily in favor of "sprinters" over "marathoners". That is, they select for people who can go from nothing to working code in a short period of time.

I am one of those people who takes a while to get rolling, especially when starting from scratch. Interviews generally give you 30 minutes or an hour to produce something. I will easily take an hour to think about the problem, do some research, and then create some notes before writing any code.

This is, of course, not what most companies want. Unless you are asking me to do something trivial or something that I have claimed to do many times in the past, you can't expect me to come up with the "right" answer instantaneously.

I never jump right into editing code, unless I am already intimately familiar with it.