Personally, I've found training 3 days a week to be the best. I got this routine from Dorian Yates book and it was the rountine he used for 4 years in the lead up to his first crack at the British Championships in '86.
Basically it was a 2 day split:
Workout One
Chest
Back
Delts
Abs
Workout Two
Thighs
Hamstrings
Calves
Biceps
Triceps
Both workouts took approximately 60 mins
And the split was like this:
Week One
Monday.........Workout One
Tuesday........Rest
Wednesday....Workout Two
Thursday.......Rest
Friday...........Rest
Saturday.......Workout One
Sunday.........Rest
Week Two
Monday.........Workout Two
Tuesday........Rest
Wednesday....Rest
Thursday.......Workout One
Friday...........Rest
Saturday.......Workout Two
Sunday.........Rest
It's a brutal routine, and is both physically and mentally demanding, but the results will speak for themselves.