I had a couple of broody hens that I moved to a tractor thinking they could set some eggs and not be bothered by other hens laying on top of them. They were so upset to be in a new place they stopped being broody.
What breeds of chooks do you have? Some breeds tend to go broody, others rarely if ever go broody so your chances of getting a broody hen really depend on what breeds you have to work with. It seems like I waited forever for my first broody and then had five of them start within two weeks of each other....
I used to worry about mine going broody, but then my oldest girl (who never was broody) became an internal layer and from reading all the posts and threads I realized it was because she had laid so many eggs in her life that her reproductive tract eventually became so scarred that the eggs just couldn't pass through. It's not a nice way to die. So now when my go broody, or don't lay so much in the winter, I think of them as just taking a break and resting and I don't mind.
I still take them off the nest once or twice a day when they are broody so they get enough to eat and drink and a chance to run around, but aside from that I don't worry the way I used to.