I don't incubate quail eggs, I only deal with chicken eggs (and maybe geese this coming Spring). But I USUALLY do a constant add/rotation with my eggs. Only the last few times have I added eggs all at once, and then waited for them to hatch all at once. My flock is still fairly small, and they say you *should* only keep eggs for 10 days before putting them in the incubator or fridge. If I did that, I would waste incubator space!
But what I've realized is that the humidity is just fine at about 50% the entire time, even during hatch. I've never raised my humidity for hatch. Ever. And the very first batch I did like that was a 100% hatch rate!
Right now I've got eggs in my incubator ranging from a hatch date of September 27th (tomorrow) to October 17th (three weeks from today). This is how it usually is for me, and still no problems.
I've actually never gotten the entire idea of raising humidity and lowering temperature anyway. It's not like the hen can really lower her own body temperature and sweat heavier when she's sitting on them! But I use a little giant, and I keep water in the trays, I keep the temp at a constant 102, and I write dates on all of the eggs so I know who is due when.
But even better, I found out in the last two hatches (when I "rescued" eggs from a broody hen that hatched a bunch and then abandoned the rest) that apparently you don't even NEED to take them out of the egg turner! Actually, after that first mistake with one, I realized that hatch rates seem BETTER when they are left in the egg turner! I've had better hatch rates by just leaving everything alone, than I have by trying to adjust everything and keep it perfect.
So don't worry about it. Just keep the humidity around 50%, keep the temp between 99 and 102, and let them do their thing!