One thing i speculate about incubation time is the Facehugger implantation variations.
I like to think the facehugger in Alien stayed on Kane's face longer than Oram or Lope in AC, due to the eggs being in stasis on lv426 for a period of time, so the metabolism of its purpose was slower.
It's funny at the dinner before Kane chestbusts that Ash is observing Kane closely as if he's waiting for it to happen at any moment.
In Aliens, the incubation time of the first face hugging of Newts Dad might have taken as long as Kane but a few more face huggings after and the Queen & nest established, the incubation period then speeds up a bit again.
Of note in Alien 3 is the Queen incubation time in Ripley that we see takes a week. I thought maybe the hypersleep Ripley was under at the time would have had an effect but as the source of the egg in Sulaco is a unsolved mystery hard to say
The creatures in the prequels you could argue are 1st generation, fresh from the source & potent with the black goo so their incubation periods and growth rates are much quicker as a result
