Nothing wrong with addings reps/sets, especially reps. Too many sets per week can be bad, but there really isn't a thing as too many reps per set. There are multiple studies that basically just show that you can make the same hypertrophy gains with high rep sets compared to moderate rep sets.
And it's a good idea to change things up often, for example the Renaissance Periodization (RP) guys, often do something like this for example: weeks 1-5 moderate reps 8-12, weeks 5-10 metabolic phase high reps 15-30+, weeks 10-15 low reps 4-8.
If you do something too long, it might not/and most of the time won't produce as much results as it did in the first 3-5 months for example.
That's why many powerlifter for example do heavy work in-season and off season they spent all the time doing high(er) rep work to build muscle and do some condition work also. If they would stick to the exact same thing all year the progress would be way worse in most cases.