Friction shifting "accuracy" has a lot to do with the ergonomics of your hand & shifter.
As I went from 7 to 8 to 9 speed on my Rockhopper (with friction thumb shifters) my shifting got more precise.
At the time, it was my only bike.
When I got a 2nd bike with trigger shifters, my friction shifting skills went down the tube big time. I ended up putting trigger shifters on the Rockhopper after a short time.

I expect you'd have enough "range", but you'll probably have to have the cable adjustment dialed in quite closely to utilize the full travel of your shift lever.