I strop at the same speed on both. You dont need to strop at warp speed, just a smooth comfortable stroke that ensures the razor makes good contact with the strop.

I usually do 30 material and 60 leather before each shave, and then 15 material and 25 leather after the shave (after cleaning the razor) to ensure that the edge is totally dry and free from any microgunk.

It really extended my time between honings when I started stropping after the shave as well.