There are unsurprisingly lots of variables.
The various tribes free range here and have multiple coops and other nest sites to choose from.
I prefer hens to sit and hatch in their tribe coop. It makes integration so much easier and the chicks hatched with the rest of their tribe around them tend to learn faster and have a better survival rate.
Problems can and do arrive when a junior hens tries to sit and hatch in the tribes coop.
Some senior hens will drive the junior hens off her eggs. This isn't because the senior hen is just plain horrid, it's because as senior hen she has demonstrated her ability to get to be the senior hen and in chicken thinking it's her genes that should go forward; not some unproven juniors.
Mostly here the junior hens will try to sit and hatch away from the others because she knows she is junior.
I try to ensure that the senior hens are the hens that sit and hatch if possible. I want if possible her genes to go forward as well.
I rarely let pullets sit at all.
So, if she is as you write a junior hen then it may be best to separate her. Unless you are desperate for chicks I wouldn't let her sit at all and would wait for a senior broody.