We are in the end of our first batch this year and I started with 32 chicken eggs and 15 duck eggs in the incubator. The chicks started hatching early Tuesday am (4/6) and have pretty much stopped as of yesterday. There are still 12 chicken eggs left - we have so far gotten 18 chicks. I'm thinking that the remaining 12 are no good or didn't make it, which is pretty sad, but ours rolled all over the eggs when first hatched, too. 1 chick didn't make it past the pip, but had made a nice hole; not sure what happened there, but another egg was thrown out early because of a crack.
The ducklings should start hatching on Tuesday 4/13 - when the chicks started hatching I pretty much let them take care of the rolling for me! The only problem I now have is the mess the hatched chicks left behind. I have started turning the duck eggs again because no more chicks seem to be hatching, but I left the remaining chick eggs in there just in case they decided to wait 3 days after hatch date to come out...cross your fingers! I, too, wonder if the rolling by the hatched chicks is what is causing the remaining 12 eggs to not hatch...
I'm definitely going to try the egg carton hatching with another batch we have going in another incubator (should hatch on 4/27). That way the hatching chicks leave the other eggs alone and stop making so much of a mess!