you want to give your body at elast 48 hours to recover.
That is , if you do bench press on monday, wait at least until wednesday to hit it again.... and know that you are more than likely overtraining that bodypart.
I think the general rule has been to wait a week between bodyparts.
Some people do an entire body workout 3 days a week though and I am not sure what the deal is there. I'd say overtraining and not letting the body rebuild enough between workouts, but it appears to do good for some people out there. Possibly their bodies are recovering much faster, and possibly they are not lifting with as much intensity as some. I dont know.