Oh my God! A non-rant! This is a very cool article about creativity (you have it, you can cultivate it) in the Wall Street Journal. Helpfully, it distinguishes between the situations that require insight--where you should relax and distract yourself and let your subconscious do its thing--and those that quite you to just keep plugging away.
This ability to calculate progress is an important part of the creative process. When we don't feel that we're getting closer to the answer—we've hit the wall, so to speak—we probably need an insight. If there is no feeling of knowing, the most productive thing we can do is forget about work for a while. But when those feelings of knowing are telling us that we're getting close, we need to keep on struggling.