I primarily shoot Fuji acros 100 iso film with my 6x6 Hasselblad. Normally I stop my lens down two stops from the wide open position.
Interestingly I was enlarging some Acros negatives shot in my Bronica SQ-B the other night. I could only see the grain when enlarged to 18" square on the baseboard and then it only looked like a velvet texture. Film developed by me in Rodinal 1:50 and using a new Scoponet grain magnifier. With the head moved down to make a 7x7 there was no hope of seeing any grain, I did try but it found easier to just eyeball the projected image with the lens wide open. Didn't have this problem with 35mm.