Preshave; I normally do 20 linen and 60 leather. I could probably get by with 10/50. If I feel I need to do more then its probably time for at least a Crox touchup or back to the hone. But, a lot of this depends upon your shaving,stropping style, your beard and the razor itself.

Edit; PS; after the shave and dry off of the razor and before I oil the razor I do about 10 laps on the linen just to make sure the edge is clean and dry.