Most trainees overtrain ...train too often, too many sets and don't carefully track their progress/gains objectively. Having said that, many of these studies use newbies as research subjects. Most of the gains in "strength" a raw recruit will experience is due to SKILL not actual strength improvement. Even a barbell curl, a uni axial movement where you'd think no skill is involved ...nope. I'll guarantee every trainee learns to "game" it. They want to get stronger and will find ways to make the exercise more efficient...ie skillful. After 3 or weeks of break in training, where everyone learns most of the "game" in the movement that's where the measurements should start...in research subjects and personal trainees. That's where the real strength progress is a reliable measure. Every exercise has two components: Skill and strength.
Many, yes, but not all. And with relatively few exceptions, the conclusions drawn are roughly the same.
People who seek strength find ways to make the weight seem lighter. People who seek hypertrophy find ways to make the weight seem heavier. Think about that for a bit.
I do reps until failure, rather than stopping at an abritrary number. I'm still young and referenced the Walcott study because it had specific numbers. I saw it in a book called Weight Training for Dummies. This basic and humorous book is most of my knowledge base regarding weight training. I became interested in the body's energy systems because I could outperform my much more athletic friend in certain activities, such as kayaking and high altitude mountain climbing after about twenty minutes of competition.
To put a finer point on it, people who seek to display the appearance of strength find ways to make the weight seem lighter.
Okay. When I was young, I did a lot of volume 3 times a week. I was able to get away with it because I recovered more quickly than I do now. Looking back, I'm not convinced I was optimizing. Should you ever be in an experimental mood, consider doing your workout twice a week for a couple of month or so rather than the 3 times you are doing presently. If you ever decide to give it a try, please let us know if you noticed any changes in strength or body composition.