If you are training once per week, depending on your intensity per set, you should try to stay around 8-10 sets per bodypart. If you train like Yates does, then 8 will suffice. If your level of intensity is that of most though, 10. Try to put as many exersises into that ten sets as you can to hit all angles. For instance, my Chest workout today went like yeah..
Bench: #135 x 10, #225 x 5, #315 x 2, #345 x 4.
Incline: #135 x 10, #225 x 10.
Dips: 2 Sets of 15 done slowly. No weight belt at my gym for weighted dips, so I do them this way.
Dumbell Flies: #40's x 10. #60's x 10.
Then I did Shoulders. For that group I do more sets(12) as you have 3 heads to hit. 2 exersises @ 2 sets apiece for each head for those.