I have a different view on this, especially with the rare tolbunts. And let me say I respect your decisions but I find sometimes Its my fault like the humidity was too low and the shell is rock hard that no chick could pip through . dont mean there is something wrong with the chick. It just wasnt incubated right or mama ate way too much calcium. I have assisted a few times with success and no future problems with later hatches but because there can be so many reasons / things that go wrong its a very hard call to make.
I understand your reasoning and respect that too granny and it's very true that there are many reasons on non hatchers or strugglers. I have just spotted a pip

There is life in there! I have helped some at the end of hatch and they have gone on to be good chicks others I've had to cull or they passed. I will only have a look at helping though at the end if they have still not finished their zip.
York, what day are your eggs on?

Day 20