I now hatch in cut-down paper cartons ONLY. I wasn't happy with my hatches when I had them on the side. One would hatch and climb over the other eggs that started pipping and then they lose their place and died.
I followed Wynette's advice and started hatching in cartons and have had near 100% hatches (for the ones that went into lockdown,that is) It is so incredibly cool. First of all they have been developing in that direction for the last 18 days so keeping them in that position makes sense.
They start pipping right along the edge of the air sac and zip all around the egg and literally POP out. They don't disturb any other eggs.
At first I was skeptical, but I trusted my mentor, Wynette and it's the only way I'm going to hatch ever.
Here's a picture of hatching. What is the most critical is that they hatch and you allow them to rest, sometimes all slumped over in the egg (they are still absorbing yolk) and do not disturb them. Do not try to help them, do not remove the cover. If you can't stand it, then "go run an errand" a quote from my mentor. They can do this hatching thing all by themselves, if you maintain temperature and humidity.
Now a bit more advice about humidity. If there is a situation and you MUST open the cover...let's say a day has passed and you want to get the babies in the brooder..... get a sponge soaked in Hot steaming water to place in the bator that you are removing the chicks from. It immediately will raise the humidity to what you had before you opened the lid. Just keep an eye on it, and remove it if gets too high. This helps any of the eggs that have pipped from becoming shrink-wrapped.