Do I need a lot of variety?
As far as hypertrophy goes, some of the biggest mistakes people make is adding too much variation and never fully mastering any movement and on top of that, executing it poorly.
If you’re trying to grow your pecs, for example, your first concern should be to actually train the pecs.
Muscles grow when you apply tension. In order for the muscle to exert that maximum amount of tension, there needs to be a certain level of stability.
Think about it, muscles are anchored from 2 points (origin and insertion). When you perform an exercise, you need one end of the muscle to be fully stable or stationary (like an anchor) so the other point can move with full range of motion and be fully tensioned.