I had one egg that pipped low and no progress for almost a whole day so I did pull that egg out, and the ones that had hatched at that point too while I was at it.
It was too late to help the low pip - chick was 100% formed and yolk absorbed - I think it just suffocated as it didn't pip in the air cell.
My bator holds temps and humidity very steady even when you open the lid for a moment. It's a plastic cooler and I think the height/large interior space of the cooler, coupled with the superior insulation as compared to styrofoam makes it more forgiving of opening the lid during incubation.
The humidity dropped maybe 2% and then back up with in a couple min after I closed the lid. Never dropped below 70% since I closed the humidity vent holes and added my sponges back on day 19.
Also, I dry incubated this batch - didn't put any water in the first 19 days at all. Humidity held between 40-50% - the ambient humidity with vent holes completely open the whole time. It was somewhat of a test hatch for me. I would have added humidity if it had dropped much lower, but as it was I wanted to try the dry-incubation method. I used the egg carton hatching method for the first time too. Not sure if I like the egg carton hatch or not - it made it harder for the camera to get a good view of the pips, but I did like how the eggs were held steady and not bowled around so much. I'm somewhat ambivalent about the carton method.
If these last two come on through I'll have 16 of 28 - still over 50%, and if you take out the 5 clears then that's 16 of 23 - 70%. Not bad for shipped eggs - and considering how many clears I had, and two or three of them had totally loose yolks, I'm thinking these had a rougher ride through the PO than other shipped eggs I've gotten.