it's funny...
Kinda funny but from the research I've done it actually takes about 7 days for a muscle to totally heal (on the cellular level)
Watch a cut one time, it usually scabs over in a day or so, then the scab flakes off...anyways, about 7 days later it's just a wee scar (within reason, a missing limb wouldn't be a "wee scar" but were talking a little cut here) Kind of a bad example, but thats sort of how it works, the micro damage takes i think it was 72 hours to heal, then another 72 hours or so to rebuild itself stronger. Mind you, this is after a REALLY intense workout, like 45 minutes of pecs, or arms, or back, you get the picture. But when it comes down to it do what these guys are saying...listen to your body, and adjust your workout to what feels good for you. And also mix around your reps/weight a bit, going with slightly lighter weights that you fail on around 10-12 reps promotes hypertrophy (thickening of muscle cells, and cell walls) where as working with much heavier weights that cause you to fail at 2-4 reps promotes hyperplasia ( the recruitment of new stem cells to grow new mucsle fibers)
Theres also fiber splitting and who knows what else!both forms will do a bit of both (hyperplasia and hpyertrophy), but encourgae one more than the other depending on which rep pattern you use. So basically what I'm saying is that with slightly higher reps to failure your muscles will bulge more (bodybuilding style), but with lower rep ranges you'll get more power than bulge. Of course if your starting out either method will help you grow big, and it also depends on what your goals are.
Phew! Little bit off topic, sorry guys, hop some of this was helpful!