Every week or two. And machine drying, on the lowest heat setting possible.
Jeans used to stand up to that. Maybe I’m washing them “too much” (wars have been fought over the Right Way to do denim care) but since they used to handle it just fine, I know it’s possible for new jeans to do it...
I’d suggest you not wash your jeans so often. If you think they’ve gotten some gross stuff on them just hang them and spray some disinfectant spray.
I wash my jeans every couple months, I just use a bucket and then hang them to dry for a couple days.