But I do agee with arnold's saying
If you want 3-D looking muscle you have to work them 3 dementionally meaning to hit them muscle from all kids of different angles.
That is where his training ideas came into play lots of sets with different excersizes for the muscle.
Arnold claimed if you want wide upper arms you need to train them for width , if you want peaked bicpes you need to train the peak,if you want thick inner bicep width you need to train the inner bicep if you want thick outer biceps you need to train the outer bicep head.
Arnold applied that idea to all of his muscle wich inturned lead to working each muscle with 4-5 excersizes for each muscle.
Then arnold idea was the more you train the muscle the better looking it gets
so his volume traing was really upped towards contest time to bring out shape ,cuts seperation ,density.
Also arnold followed basic lifting routines and threw on most of his bulk in his late teens and early 20's then spent the last 4 years from 71-75 really just refining and polishing what he built with more of a basic routine for his early years
So arnold prob needed that many sets and reps by 1975 becuase he had already had 12 years of bodybuilding under his belt and needed the extra stimulation or the muscle becuase they were so used to training
for someone starting out to jump into arnolds routine that he used after 10 years of traing would be like asking for disaster.
So dont get cuaght up in over training , It is to eazy to do , The endorphin rush from bodybuilding can very great and make you feel awsome but you have to relize rest is just as much if not more a part of bodybuilding then the actual weight lifting itself