Throughout your training career you are likely to experiment with many different types of programs. Bodybuilding, strength, power/athletic, or some combination thereof. Some people make the mistake of finding a program or training style they like that works for them (at the time) and just run it non stop without ever making any changes.
This is a sure way to stagnate progress.
While you shouldn’t jump from program to program every month or try to “confuse the muscles” as some trainers say, you should have some variation in your training programming over a long term time horizon. Bodybuilding style training with lighter weights and higher reps will increase muscle mass and give your nervous system after a long strength or power block where weights are high and reps are low.
This increased muscle mass will lead to greater strength gains/ability during the next strength and power cycle. On the flip side, strength and power training will allow you to move heavier weights in the bodybuilding phase which will further increase muscle mass.
As you can see, this is a self-reinforcing circle that will lead to continuous gains in strength and muscle mass over time. I recommend running ~3 separate phases throughout a calendar year depending on the progress being made.
If you are still making great strength gains and don’t feel beat down, you shouldn’t switch to a bodybuilding phase just because it’s been 3-4 months.
Milk everything you can out of each cycle before you move on to the next and you will make astonishing gains over time.