No, that is actually justified. Imitrex cannot be used more often than 6 times a month. Otherwise overuse can cause what is called "rebound migraines" or migraine medication overuse attacks.

Even Ubrelvy can currently only used a certain number of times a month. Nurtec which I am on is used every other days as a preventative. I think Ubrelvy may eventually be tested and approved for preventative use, too, but we are not there yet.