It is also very helpful if you've sized your drawer a little too large or something came out a little bit out square (....not that I've ever done either ...really, I have NOT - they are WAY over/undersized and A LOT out of square ). Bevel the endgrain edge and then you can plane the entire side in one direction or front/back without blowing out the endgrain of the tails (when planing front/back) or pins (when planing sides). If you don't bevel, you're left with trying to deal with tear out on the long grain surface or aligning and clamping a backer board...at least this is something I recently figured out. I'd wager it is "common" knowledge to some.