Really your set up is what should really determine this. And your expectations. I have found, that they know more about being a chicken than I do, and let them do it their way. I try and bother mine the least possible. I have a large enough coop for my flock and a 600 square foot run. In confinement, mine have enough space.
Once years ago on here - people turned in the eggs they set and hatched. Incubators and broody hens. Over time with thousands of hatches recorded - the percent was very close to 50% of the eggs set produced live chicks. So that is my expectation. If I get above 50% I think that is grand, but I set eggs knowing that it is unreasonable to expect that many chicks. "Don't count your chicks until they hatch" is based on real experience.
I read an article on here - I have only seen it once. To put a good healthy scoop of soil in the nest they have chosen. And I think it helps. I added a bit of bedding to the sides - and hollowed out the center. I mark eggs with the sharpie. I have found with medium sized standard birds, I do better with a clutch of 8 eggs verses 12 eggs, but I have found that mid summer, you can hatch bigger clutches.
My birds have been laying for months, so I took out the fake eggs in the other nests. In the past, I have had a hen sit on the correct nest for days, and then come in to find her on the nest next to it! I just move her back and have hatched just fine. But the last two times, I removed the fake eggs, and they have gotten on the right nest just fine every time.
I think it is better for her to get off her nest, go out get water and feed and terrorize the layers. With my first hatches, I worried about the layers, but anymore I don't. Mine get her live chicks out of a nest that is a couple feet off the ground, and introduces them to the flock on her own time, in her own way. I switch to chick feed for everyone, with oyster shell on the side.
If I do not catch her off the nest, where I can peak at the clutch, every 2-3 days, I carefully remove her from the nest carefully, and check the eggs. I also count the eggs from the layers. Once in a while I will find a stray egg, but not real often. But mostly I ignore her.
I have had two hatch the same day - and raised them together, even though they were in separate nests to incubate. Recently, my neighbor thought she had lost 2 hens, only to have them come back with 17 chicks following both of them.
Nothing is more fun than a hen with broody chicks.
Mrs K