I've tried a variety of sizes and the width never really seemed to matter much to the razor. Narrow strops (like short strops) need more laps to get the job done, but this doesn't really seem to be much of a factor until you get down to the 1 1/2" width.

Now on paddle strops I definitely prefer the 3" or 2 3/4 " widths, but on hanging strops the natural flexibility seems to make them more forgiving of sleepy stropping.