It depends on the doctor, but it's not daily forever.

Brassard's routine is 4X daily for 20 minutes per session for the first month; 3X daily for 30 minutes for 2 months; twice a day for 30 minutes for three months; once a day for 20 minutes for six months. At the end of the first year, gradually taper down to once a week, 15-minute session, forever. (There's some stuff about which dilators to use and how often, too, but that's the basics. The lifetime maintenance dilation will be with the largest dilator only.) I may be fortunate, but for me prep time and clean-up adds only about 5 minutes and it takes me zero time/effort to get to full depth, so for all intents and purposes that's the real time I spend dilating.
Dilation maintains depth; it's usually possible to gain width at any time (at least up to the limits of the pelvic aperture) by gradually, gently increasing size.
I also hear from some lucky women that once they're many years post-op it's possible to drop to once a month or less, and one or two even quit altogether. For that matter, I know people whose pierced ears don't close up either! So I guess some bodies are more cooperative than others.
I'm currently just barely to the once a week phase, but I have to say, 15 minutes a week is no big deal. I spend more time doing the dishes every single night.