My Vet says Yes, for life...My dog prefers the Royal Canin over Science Diet. However, she will only eat the canned. (Not the dry).
Even though it will probably be a bit more pricey than your regular dog food, it can't hurt.
My dogs were prescribed W/D for different stoamch issues, and now I keep them on it. I spend over fifty dollars a week on dog food, but I believe it's worth it.
My cat is on special urinary tract food, because he is a manx and that breed of cat is susceptible to bladder stones, which he had last summer.
The vet said as long as he stay on the special food, he should have no more problems.
And so far so good!
I work with a nurse who's beagle has a bladder stone and it was dissolved with diet alone.
I believe they told her that yes, her dog will have to be on it forever.
They need to ID the stone when they remove it, then they'll know the best way to prevent more. Plus, the stones are usually accompanied by bacteria, which encourage stone formation, so antibiotics for a long time will probably be prescribed.