As a maybe 1000-time-R-Gacha spinner I seen:
1) 50 min (most common)
2) 60 min
3) 90 min
4) 2:00
5) 2:30
6) 3:00

I even got all 3 limmed girls with just one R-Gacha but only once.

I just started to collect new data from Kurito