Or, it could be that the bacteria and other nasty stuff that gets into the eggs that we cannot see make the baby weaker and gives it a slower start. As for how do you know if there is something wrong, you cut a very small "v" in the egg. Without digging around, how do you tell if there is a problem. The cut window is so small, all you see is the side or back of the snake. And, unless the cord is wrapped around that specific spot, you may still miss it. So yes, cutting may let you see a problem, but it may also be missed even with a cut, unless you are making big cuts (letting in more junk).
Please do a search on this form for problem eggs. There are many many threads where cutting early caused all kind of issues. I think it may be the number one reason that babies are lost. We all want to see what is in those eggs. We have slaved over these animals for a full year to get to the point where we have eggs in the incubator. I know it is hard to wait, but if you do not have the experience to deal with the problems you may find, then the best avenue in my opinion is to let them pip on their own.
Just my 2 cents, your experience may be different.