I THINK...not sure, but it seems that if you wait that long the muscle repair will have already started, and you may be actually hindering growth by tearing it down again. I know you should let the muscles rest 24-48 hours to repair, so I THINK (key word) this would not be a good way to train.

Less is more.

The body needs time to recover after a workout. Recovery time is very important for muscle growth. Like it was said earlier--less is more.

I personaly think it depends on your goals, and whether you have any. elite athletes use multiple workouts a day to get in the volume they require to increase strength.

for the most part i would think that the risk of overtraining would be high, and the inability to eat enough for the demands of a rigorous multiple workout training schedule. not to mention the need for more sleep.

I would guess the way to figure out if this is appropriate is to figure out what your workouts total in hours and be unable to image making them any longer, and be out of days to work out in.

an example would be your workouts are 2 1/2 hours each, 5 days a week, and you are not gaining any strength, and the workouts are easily recovered from. I think this would warrant shorter sessions throughout the day.

if you really want to start building muscle, try cutting out some of your cardio(aka anti-strength excercises) and adding in more squats and deadlifts.

also getting bumper plates may increase your compound movements. you can add stuff like front squats, high pulls, standing push jerks, powercleans, snatch deadlifts.

Working one body part in a work out session is fine, but doing it over the span of a day as you suggest is not going to give you muscle growth that (I assume) you intend to achieve. In order to grow, a muscle needs to be stressed and worked to exhaustion so that the fibers of the muscle are broken down and can regroup for the next session. Breaking down the fibers of muscles requires sustained energy and not intermittent excercise. Hope that this helps