Once A Week v. Twice a Week

[LOKITSC]

I've read that training each muscle group twice a week is over training. I've also read that training each muscle group once a week is under training. I know that everyone is different but I'm curious which most of you prefer. My intuition is that varying the frequency of work-outs is probably a good thing. Also, if you're using heavy weights, once a week may be preferable. What do you guys think?

[diamonds]

I switched to twice a week training a while back and got some pretty fast results. However, the results stopped abruptly and started over-training myself into a downward spiral. People probably feel better training twice a week because they always have a pump. You don't have to lift once a week either. Don't lift like this:
Monday: chest/tris
Tuesday: back/bis
Thursday: Shoulders
Friday: legs
--wait until monday and start again

If you set up your program based on days on/off you will hit each muscle once every 5-6 days. You just need to group muscle groups

Day 1
Chest: Smith Machine Incline Press 4x10,8,6,4 (1 warm up set 10-12)
15 degree Decline Bench 3x8
Dumbell Flyes 2x10

Shoulders: Dumbell Shoulder Press 4x8-10 (1 warm up set 12-15)
1 Arm Cable Side Laterals 3x10

Triceps: French Presses 4x12,10,8,8
Pushdowns 3x 4-6 (double drops)

Day 2
Back: Lat Pulls (wide grip) 3x8 (1 warm up set 10-12)
Bent-Over Rows 3x10-12
Seared cable Rows 3x8,8,6,6

Biceps: Straight Bar Curls 3x8-10
Incline Dumbell Curls 3x10-12

Day 3:
OFF

Day 4:
Legs: Smith machine Squats 4x8-10 (2 warm up sets 10-12)
Straight Legged Dead Lifts 3x8
Hamstring Curls 3X10
Leg Extensions 2x10

Day 5
Off

Day 6
Triceps: Close Grip Bench 3x8*
Overhead Extensions 4x8

Shoulders: Smith Machine Shoulder Press 4x6-8
Upright Rows 3x8

Chest: Dumbell Bench 4x6
Dumbell Pullovers 2x8
Weighted Dips 3x12-15

Day 7:
Back: Dead Lifts 3x8 (2 very light warm up sets 10-12)
Back Extensions 3x15
Behind the Neck Pulldowns 3x10

Biceps: Cambered Bar Curls 3x8
1 Arm Spider Curls 3x8

Day 8 & 9 Off


Day 10:
REPEAT CYCLE