Re:
Agreed.
Magazines and even the EAS body for life program would have you believe multiple sets are the "best" way to workout.
BUT, muscles only grow for 1 reason, fatigue/work above and beyond what they're used to. Growth is the result of this, and a muscle adapts or it tears.
Sets that don't push this threshhold @ a high enough rep range are just cardio sets, since you're really only burning sugar/fat, but not pushing the weight/reps up over what you did last week.
LOTS of people ask me why I do 1 exercises with a few sets or why I'm in the gym under 1 hour...what are you there for if you're there longer or doing more?
Isolation exercises are cute, but if there's anything I learned from Powerlifting, THEY are only used when your supporting muscles are stagnating. Such as when triceps aren't growing with chest strength. Chest strength is a matter of a system, since it also relies on the Triceps and Front Deltoid, and to some extent the Lats (since you PUSH up). If you go big, and constantly grow with Chest exercises, as a BY product, your triceps and front deltoid HAVE to grow, otherwise you can't lift more weight. It would be IMPOSSIBLE.
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Alot of what APPEARS to be pyramiding, is merely a few warmup sets of 12, 8, 4 etc, until they do 1 all out set or some combination thereof for X reps ( say 6 to as high as 50 depending on the exercises). Volume might empty muscle glycogen stores, but the goal is strength, is strength comes from more muscle, more muscle = strength, and the only way to do that is consistent, growth and progress each week.
A-Unit