I don't find you get uber keen edges from cotis. I have used a few they are tricky stones to learn and can slurry dull. Even when I have had blinding hht results the shave feels butter soft, a kind of delightfull dullness which is very forgiving. I like coticules and prefer these edges, I think that's how they are supposed to be.
A tip if you want to eek out a bit more keeness and keep that smoothness is to max out on coti, go to paddle strop loaded with crox (TI crox is my favourite) say 10 to 20 light laps. Then come back onto coti with lather for 10 laps. Shave see what you get, go another 10 laps on lather till you dial in you smoothness you prefer.

My 10 cents
Joe