Everyone's growth potential is different.
Some people respond better training each body part 1x per week with high volume, and then allowing ample time for recovery.
I respond better training everything twice within a seven day period, using only one compound, multi-joint exercise for each body part. By only using one exercise, it keeps me from overtraining.
When using a regimen like this, i like to perform all upper body movements on one day, and all lower body movements on day two. I will repeat on days 4&5 with alternate exercises.
Ex.
Day 1:
Flat Bench Press: 4x5
Military Press: 4x6-8
Pull-ups:4x6-8
BB Curl: 4x8-10
Lying Tricep Ext:4x8-10
Day 2:
Squat: 4x5
Hacksquat: 4x6-8
Leg Ext: 4x10-12
Leg Curl:4x10-12
Hyperextentions: 4x25
Day 3:
off
Day 4:
Incline DB Press: 4x8-10
DB Shoulder Press:4x8-10
Low Pulley Row: 4x8-10
Preacher BB Curl: 4x10-12
Close Grip Bench: 4x10-12
Day 5:
Deadlift: 4x5
Leg Press: 4x6-8
Stiff Leg Deadlift: 4x10-12
Calve Raise: 4x25
Hanging Leg Raises 4x25
When i reach a plateau.......I change it up!