I call bullshit on that. Bis/tris is an exellent combination. Obviously, there will always be individual differences in what works and what doesn't, but generally speaking, back/bis is no good. Like you guys said, the back training will have the bis pre-exhausted so you cannot maximally load them when it's time to do bis. Also, bis are a small muscle group and it would be optimal to stress them more than once a week. By separating back and biceps you get in essence 2 bicep workouts a week (that is, if your training cycle is 7 days). I also believe in the POF (points of flexion) method of training:
For instance, do
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*2 sets of straight bar curls 8-10
*1 set Incline DB curls 8-10
*2 sets Incline DB hammer curls 8-10
*1 set Cable flexion 8-10 ( I don't know the proper name for this), you stand between 2 cable attachments, kinda like doing cable crossovers, except in this exercise you're supposed to be upright. Grab the upper cable handles, and flex your arms bringing them close to your head, kinda like doing a double bicep pose. Hold the peak contraction.
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In the barbell curl, maximum stress is on the mid point of the positive phase, when your arms are at a 90 degree angle to the ground.
Then next come the incline streching movements, which exert maximum stress during lowest part of the lift . Finally, in the contraction movement, maximum stress is at the end of the positive phase. So the routine has
-Mid point maximum stress
-Lowest point maximum stress
-Highest point maximum stress
You can use the POF principles with any body part, ie. for triceps you'd do close grip bench for midpoint, behind the head extensions for stretch and rope press downs for highest point & contraction. Keep in mind the low volume is meant for drug free athletes. I believe GENETIKING is also a POF follower.