Hello,
It's usually not good practice to leave eggs in the nest. Doing so will not make your hens go broody. It just means the eggs sit there and potentially get old, dirty, broken. If you leave a few golf balls in the nest, the hens will be fooled and think that's where they're supposed to lay, and you'll avoid all that, until you do get one that's broody.
Hens go broody depending on hormones/laying cycle. Usually, they go broody in spring. You can't control it. And if they do go broody, they'll set fine on golf balls, which you can replace with eggs at the right time (once you know for sure the hen is good and broody).
It's also not good practice to let them roost in the nest box. When the hen doesn't roost on the roost, but sets in the nest box, that's how you know she's broody, well, that and the grouchy, screeching behavior, clucking, etc.