Yes.
That chance is calculated for each item you craft - i.e. when crafting 20 leathers from 40 hives, the chance is played 20 times.
This means that you can make up to 20 critical crafts and 40 leathers for 200 < CP < 300 and 20 CP or you can make 0 critical crafts, 20 leathers and 0 CP.