The warm bath I provide (35 minutes in the morning & another 30 in the evening) makes all of my Tortoises go to the bathroom. & I feel better that they do. Less mess in the Substrate, & you know they are not constipated or dehydrated etc... My Leopard drops more waste in the morning & there are a few times when I have to scoop up her waste...
Just make sure and not over do it. Stars are one of the species that are more prone to exoskeletal infections or bacteria. Especially she'll rot, in addition to keeping them very humid parts of the seasons already. Just make sure and dry them off. Also if they start getting "poofy" legs and neck there getting too much water I.e water retention and will have to pass the excess water. I'd just go with once a day.
sunlight would prolly make it more natural feeling but i dont see how it matters. i soak my tort every other day. he has yet to ever poop in the substrate yet idk bout pee. but i agree with only soaking it once a day