I can think of a few reasons...#1 hunting pressure, if you have a good buck that you are quite sure is residing there and there are other hunters about, then go after him.

a question equally important as 'how close' is 'how early?' to me. If you are hunting that close to beddign areas you better be doing it in the morning...you may want to get in there 2 or even 3 hours before daylight so you are sure you beat the deer.