I'm no expert incubator person. But I have hatched over a hundred now, I will totally lose count as I hit 200 and more this year. And I confess, the "RULES" are probably the best odds you'll ever have toward 100% hatch rates. Not staggering - not using old, cold, frozen or cracked eggs, not using pullet eggs and muddy ones or all t he things they tell you not to. Do it that way and yes your odds are better. But. But nature is an amazing thing, even in an incubator, I stagger, I dry hatch, I don't lock down - since I stagger, and I'll set any egg that takes my fancy or has my concern. I've had chicks survive a spike to 134 degrees, yes that's correct.
I've had them survive mothers that didn't turn them and then left them in the mud. I've had eggs cracked the first week make it to full term, and chicks crushed out of eggs survive because of a bator. I've hatched near frozen eggs, and pullet eggs and I've gotten pretty good at helping chicks out. It's all a matter of patience, luck and timing and practice. Broodies are not perfect, they mess up sometimes worse than I do. And unless the eggs are real disaster my hatch rates for even odd eggs runs around 80% average. Frozen less than half but I don't mind salvaging a few.
The Rules work best for the most part and sticking to them increases your odds but they're not written in stone, and you get a feel for what you can handle and what you are comfortable with over time. I started with an LG, hated it and then MADE a series of home bators, finally getting one so right, I still use it, my mini-fridge one, DarthBator. Then I found an early 1900's redwood cabinet incubator LOL for 75.00. Fixed it up and it rocks, and holds 600+ eggs, but will do small batches as easily. Really nice. I fully expect to double or triple chick production this year.
I kept hearing "that won't work", and that won't hatch and you know what some of the time - they're right but nature is built to survive stresses and pressures that will kill some or most, but stronger ones hatch anyway some of the time.
Until you get a feel for it - do it by the rules, understanding the further you go from the rules, the more likely you are to decrease hatch rates, or blow a hatch. But those things are guidelines. Learn about ventilation, humidity and what happens IN your house, in your bator, with the way you do it. Keep notes. When in doubt build a bator or two out of spare parts and figure out what works and why. Sure you can hatch forever in a preset prebuild commercial bator, and probably never need to actually understand the how and why, in a good one you can just follow the rules, use perfect eggs and be happy.
Or you can TINKER. Both things are okay. I am deeply attached to some of my disaster poultry from ruined broody hatches, and sadly neglected eggs, from the rescues, and from the cracked eggs. I like that here and there I have wee ones from near frozen eggs, and Temp Spike chickens. My lap tom turkey Brit is from a total disaster hatch, unturned muddy and abandoned, so are his girls, Trace and Marin. All of them momma's birds, and only here because I not only worked with cruddy, cold, wet muck covered eggs but assisted each of them, since unturned eggs have babies stuck to the sides. And they've already produced one generation of young, normal healthy busy free range birds.
What you decide to set into an incubator is yours to choose, rules or not. If you decide to stagger, you'll make mistakes but you'll learn to succeed. You'll blow whole hatches due to disaster now and then. Happens in nature too. Keep trying. Persist and you learn. You'll have good shipped egg hatches and bad ones. And middle ground ones where you get 50-60% to hatch. The more you do, the more you practice, the more you learn, the better you do.
Don't take the unhatched egg as a personal failure. But don't blow through six bad hatches, thinking "I'm following the rules and it's not working." Two back to back Zeroes, means something isn't right, and you don't know yet what is missing in your equation. Repeated empty sets tells you something in your "parameters" is not correct. Either your thermometers are broken or uncalibrated or your ventilation is wrong. More people suffocate eggs due to that whole lock down thing, where they plug holes and try to force up humidity, than you can possibly imagine.
Anyone can do this if they persist and they learn and a bad hatch or failed chick is not always YOUR fault. Nature produces failures as well. Hang in there, and you'll have loads of fuzzies in no time. Too many, then you'll be building pens and adding fences.