I had my appaloosa on a daily wormer over two years just because I was competing so much during the summer and fall. It was just easier to give it in the grain then to keep track of what I gave and when to do it.
I wouldn't recommended daily wormers... it weakend my horse's immune system (he has had a past of ulcers and since I had stopped using the wormers and backed him up with probiotics he hasn't had the runs for weeks now).
I wished back when I was doing it to just take the pain and keeping track of it haha. Plus he looks a thousand times better since i've stopped. In the long run its not worth it I think.