it doesnt matter how many times you train a muscle in one week, muscles recover in about 24 hours, it is about putting too much stress on your CNS via training to failure, or to heavy! alot of people don't understand this. So yes it is possible to overtrain if you train too heavy or too failure too much a day even if you only train 3 times a week and are training different muscles on those three days.
For example: you will probably overtrain on a program like this:
Push:
Flat Bench 5x5 failure every set
Incline Bench 5x5 failure every set
Military Press 5x5 failure every set
Dips 5x5 failure every set
Pull
Rows 5x5 failure every set
Pull-ups 5x5 failure every set
Cable Rows5x5 failure every set
Upright Rows5x5 failure every set
Legs
Squat5x5 failure every set
Deadlift5x5 failure every set
Get the point ?!?!
On the other hand you can train the same muscle 3 times a week, but not to failuire and not too heavy all three of those days and be fine!
For example: you will probably
not overtrain on a routine like this
Monday
Flat Bench 3x10 2 reps short of failure
Squat 3x10 2 reps short of failure
Deadlift 3x10 2 reps short of failure
Bent-over Row 3x10 2 reps short of failure
Pull-ups 3x10 2 reps short of failure
Military Press 3x10 2 reps short of failure
Wedensday
Flat Bench 3x10 2 reps short of failure
Squat 3x10 2 reps short of failure
Deadlift 3x10 2 reps short of failure
Bent-over Row 3x10 2 reps short of failure
Pull-ups 3x10 2 reps short of failure
Military Press 3x10 2 reps short of failure
Friday
Flat Bench 3x10 2 reps short of failure
Squat 3x10 2 reps short of failure
Deadlift 3x10 2 reps short of failure
Bent-over Row 3x10 2 reps short of failure
Pull-ups 3x10 2 reps short of failure
Military Press 3x10 2 reps short of failure
To answer your question in short- If you are not training to failure or heavy, you can train 2-3 hours a day if you want, and not overtrain, Are you going to have more gains than a regular 30-45 minute workout- NO, Is it a waste of time and energy- YES, Is it a stupid thing to do- yes
