Well, everyone's knowledge is the sum of their experience, right? I know exactly what you mean, loveourbirds. During my last hatch, I hatched in the foam incubator in tandem with a broody silkie. I wasn't sure how many she could cover, so I was conservative and put the extras in the bator. I noticed the same things you're saying - she would get up off the nest every day and let the eggs cool off, sometimes for up to 20 minutes. Seeing that, I figured there was no way my opening the incubator to candle would have a negative impact. In fact, I was opening it way less than she stood up. Another factor is ventilation. Some people have strategies of adding and removing 1 or 2 vent plugs at strategic moments that they swear works for them. Personally I do not use the vent plugs at all for more ventilation.
I think it's less of an issue early in the hatch, and most of the big "warnings" folks give saying do-not-open are about the lockdown period. For example, half my chicks last hatch came out right on time day 21.. the others waited until day 23-24 and I ended up having to assist a couple of them when their zipping didn't progress. One chick actually pipped and never zipped, it's beak was crusted and dried onto the shell, I assume it couldn't move? Possibly because it was overdue. Possibly because 2 of the 3 chicks I assisted were a little malpositioned (head over wing not under), and they were also very large for their eggs, consuming the air cell (day 23). That chick that died beak crusted onto the shell was one of the last pips, and I question whether opening the incubator 12hrs prior to assist other chicks had caused a sudden humidity drop that killed the chick. Or maybe it was destined to die either way? Surely a mother would have gotten up to eat and drink and poo that day. What I mean is, sometimes people defend a point because it is their experience that it will cause death, just like your experience is that it won't. I don't really know if I caused that death, it's still hazy from here. More eggs.. more hatches!!
Edit: I highly value ALL of your experience and advice, no matter how varied, so thank you!!!
The small bathroom I have my eggs resting in isn't insulated very well, it's an old farmhouse and this was a strange add-on room. This is not the room I incubate in. I incubate in my bedroom (much to my husband's joy on hatch day, LOL) where the temp is a steady 75 and 55% humidity.

The truth is, I've never measured the temperature in that cold bathroom at night, but it's always FREEZING in the morning! Tonight, I have a thermometer in there that will show me the record low overnight so I'll know. Outside temp is expected to be 30.
I tossed that cracked egg, and I can't get any good candling photos to come out. Even though the egg is illuminated, nothing shows up in the photo.
How do you take good candling photos?