Mixed

Progressing resistance training by increasing repetitions while keeping load constant produces similar muscle hypertrophy and strength gains as progressing by increasing load while keeping repetitions constant over an 8-week period.

You do not need to add weight to the bar every week to keep building muscle. If you are stuck at a certain weight, focus on doing more repetitions with that same weight. As long as you are pushing close to failure, increasing your reps is just as effective for building muscle and strength as increasing the weight itself. This gives you a flexible way to progress, especially when you hit a plateau with adding weight.