What incubators are you both using?
I have two I'm using at the same time, same schedule. I find that my chicks still hatch at the same rate in either one:
The Kebonnixs 12-egg incubator:
https://www.amazon.com/KEBONNIXS-In...mzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840
This photo is my own unit. I've been having some trouble keeping humidity constant this time (don't know why, weather maybe?) so I added some glass pebbles into the water tray. It's helping to cut down the surface area of the water. I also put rubbery mesh shelf liner on the tray bottom to help with turning eggs evenly and give the chicks a grippy surface to walk on:
And Inucbator Warehouse's IncuView 27-egg incubator:
https://www.amazon.com/IncuView-Aut...4&sr=1-1-5985efba-8948-4f09-9122-d605505c9d1e
That link is actually to a newer model, with access to the water channels from the outside, and enclosed turning motor (BIG improvements!). Mine doesn't have those features:
I've made several modifications to deal with these issues. I drilled two more vent holes (for 3 total). I add water with a large syringe fitted with a long straw, and insert it through an air vent to direct water into each channel. I also added a cover over the exposed turning motor to protect it from damage.
Then I covered the plastic mesh bottom with rubbery shelf liner, fixed in place with tiny ties - then laid four smooth plastic strips lengthwise over it, to give the tray something to slide over easily but keep the eggs in contact with the liner. It works well to turn the eggs evenly. My only complaint is that I have to remove all the eggs to remove the turning tray. I don't know why I do that; maybe this time I'll just leave it in place during lockdown and hatching.
And I added insulation. I cut the shipping carton down that the unit came in, covered the underside of the egg tray with plastic wrap, filled the bottom and sides of the box with spray foam insulation, pressed the egg tray into the foam until level (and fixed it in place so it wouldn't shift as the foam expanded). Then I was able to lift the tray out (left the plastic film stuck to the foam - why not), trimmed the foam back, covered the outside of the box with duct tape.
I've also used it with a 'blanket' of towels over the unit with the vents and controller exposed, and I've used it without - and there was no noticeable difference in the hatch rate either way. I might sew an actual fitted blanket cover for it, anyway - and one for the Kebonnixs, too - just to minimize temperature fluctuations.