It takes considerably heavier weight for fewer reps between 2 and 6 and longer sets between 4-6 to develop top-end strength. As you lift weights that are close to your one rep maximum (1RM) during sets, rest time should rise to a few minutes to allow for recovery.
Training regimens for hypertrophy involve higher rep ranges of 8–12, with no more than 60–90 seconds of rest in between sets of 3–4. You will lift at a lower percentage of your 1RM as a result. It's hard to put a figure on it, but your last few reps should be almost impossible.
Hypertrophy builds muscle greatest. Muscle fibers micro-tear during activity. Muscles adapt, heal, and expand during sleep or rest days. Growth hormone, among other mechanisms, helps muscles expand at this time.
Hypertrophy training makes you stronger, but not for maximal lifting. High reps vs. big weights explains muscle fiber kinds and how they perform. According to research, the size principle activates more muscle fibers and "higher frequency muscle fibers" as force production increases.