Just in my own experience I found that I was spending too much time taking (handheld) spot readings here and there and everywhere and trying to average them or bias them to one side or the other such that I sold the meter and made my life easier, and to tell the truth I always been right on since with an averaging meter if it was in good repair. It also helps to know if your meter does in fact meter at 18% as some don't.

Perhaps the best in camera meter I've ever used is the rectangular patch in the FTbn series. Bias it one way or another and you know instantly the best reading for the subject.