Not if you want to look good, which is what shaving is about. I can grow a goatee and mustache, so what now I gotta shave everywhere else AND trim that stuff too? I don't think that it saves me time.
Okay, I think we just have different ideas of "looking good" (which is of course subjective!). I don't really see a problem with thinner areas in one's beard.
Not all jobs allow you to have a beard, and some allow you to have a beard only if it's nearly trimmed. Keeping a beard neatly trimmed is just as time consuming as shaving it all off.