It depends on the breed - some don't; some almost stay broody, like cochins, silkies, OEGB, to name a few. What kind do you have? Normally they will lay a clutch of eggs and go broody and set.
i have some rir and a welsummer roo if my rir hens go broody are thy likley to have ferile eggs and should i let the hen hatch the eggs ather than eat them.