I have done many different routines, twice a week each bodypart, once a week, full-body each workout, Smolov, German Volume Training, DC training, Instinctual training, Hypertrophy training, Max OT, PHAT, NSCA fly solo, Arnold`s routines, book routines and on and on. Not a single one of them really produced anything too dramatic. Smolov did increase my squat, but that is because you are really doing nothing but squatting, but after completing the program, it was nothing that I could not have attained with another program.
For me, the twice a week each bodypart is pretty much useless. It gets to be a chore and you get to the point where you are either training too much or too little. With twice a week, there really is no middle ground. I never saw any benefit from it. Just a waste of time.
I also never saw any benefit to full body routines. I actually got weaker doing these. I also got a lot weaker doing high volume, higher rep training (10-20 reps per set 28-36 sets each day).
For me, the best is 9-18 sets total for the day with reps no higher than 10 and reps that focus more on heavy weight and lower reps. This is what works for me and what I feel the most. The high rep, high volume is useless to me.