I do once a year with Equimax
BUT...only because I have a closed herd, clean the pasture and paddock and am very generous with straw, like all soiled out, leftover good in the middle on the wet spots and new on the edges.
I, of course, didn't start out that way, it developed over two years time. Fecals and a blood test for encysted, again after the wormer, and then off to my current schedule. If it wasn't for bots and tapeworms, who appear, no matter how clean I am, I would only go by fecals.