What shrink wrapping does is take the membrane and pull it tight around the chick. It makes it hard to move around the egg, harder to hatch, and can also "stick" to the chick so that when they do hatch, they have patches of membrane stuck to them that dries and you can't get it off easy. So to avoid that, leave the first hatchlings as long as you can until the rest are done.
This doesn't happen if the remaining eggs haven't pipped yet. There needs to be a hole in the egg susceptible to changes in the air when you open the lid. But you know how they can pip on the underside of an egg, sometimes you can't see it.
But shrink wrapping can either prevent a chick from being able to hatch, or if it does hatch, to be covered in hardened goo.