With a kitten in the house, twice a day MINIMUM. With older cats and deep litter boxes, once a day works for me.
I have a friend whom I love, who mocked me for scooping so often. When she had a cat, she kept the litter box right next to the food & water dishes, and never "scooped" the box, instead, she'd fully empty it once a week or so. She didn't use clumping, either and the smell was AWFUL.
When I tried to get her to A.) Move the litter box away from the food/water (or vice-versa)
B.) Scoop on a daily basis,
she VERY pointedly told me that I take care of my cats MY way and she takes care of hers HER way.
I do value the friendship, so I shut my mouth and just felt badly for the poor kitty. Said poor kitty, by the way, reached a year old and was being disciplined on a regular basis for spraying in the house. When I brought up the topic of neutering, I was told they could not afford it.
I got them info on discounted neutering, and they missed the appointment for the mobile spay/neuter program - it would have cost them only $40. Instead, they continued to blame the poor cat instead of recognizing their own lack of responsible action.
The cat was let out of the house "by accident" one day, and was never seen again. There are coyotes in the woods behind their house. Easy guess what happened to him, poor boy.
I just do NOT discuss pets with them anymore. We've been friends for over 20 years, and I'm just glad they no longer have any pets that they "can't afford" to take care of.