Depends on what I'm doing. I can get a quality session with 150 rounds, just like I can with 1,000 rounds.
I've lost count how many people I've seen at indoor ranges blazing through ammo, not hitting shit. Like 8" groups with a handgun at 7yrds, but they'll talk about how much they shoot as if it's a good thing. To me, that's embarassing.
Pre-Covid, I'd run between 500-1,000 of 9mm per month, and 250-500 of 5.56. Shooting once every-every other week, with one longer outdoor session thrown in (around 6hrs). Each indoor session, I'd pick maybe two things to focus on and get in the reps. Hell, I could take an hour at an indoor range just doing 1R1s and analyze what I'm doing after each rep. 100 rounds get me 50 reps of those isolated movements. Would do the same with draw 1s, controlled pairs, target transitions, etc.
Outdoor sessions were utilized to bring everything together. At that point, I'm pretty confident in the isolated movements and tasks I had been practicing between range time and dry firing, so the outdoor shooting just allowed me to put it all together and push myself while adding in other factors like movement, larger transitions, etc.