In bodybuilding, regardless of the body part, it's always advisable to hit a variety of rep ranges and even rest periods.
Keeping in mind that your number of reps and amount of rest between sets should be inversely proportional, here are a couple of examples of different rep ranges/rest periods you should use for biceps:
- 5 x 5 with 120 seconds rest between sets
- 3 x 8-12 with 75 seconds rest between sets
- 4 x 12-15 with 30 seconds rest between sets
The 5 x 5 scenario maximizes the mechanical tension placed on the biceps, which does a great job causing protein synthesis and neuromuscular improvements.
The 4 x 12-15 scheme maximizes metabolic fatigue and the blood volumization response, leading to hypertrophy (that's muscle growth, bro).
Finally, 3 x 8-12 is that sweet spot right in the middle.
If your goal is size, you want to stress all the various components of the muscle cell. Therefore, variety truly is key here. Either spend a few weeks using one set/rep scheme at a time before switching to the next one, or do all three in the same workout.