Depends on the song/style of music and how well the mic reacts to bleed. I've been using 421's on toms lately and anything that's not the tom sounds like ass. It's just really, really ugly sounding and I don't want that in my track. Also, if you're tracking in a less than good sounding room you'll want as little room tone as possible so killing the toms when they aren't being played will almost be a necessity. I've never automated the bleed like some, but I routinely just cut and make fades. I'll even do that on my ride/hihat tracks when I spot mic them because I hate excess bleed that much. Oh, be sure you do this AFTER you slip edit or beat detective the drums and have the final edits consolidated/bounced down. The chance for things to get FUBAR is exceedingly high.