Well, I never had Ginisee on an IV treatment or hock injections. I always had her on the IM injections. But I have heard that many vets want to gradually wean a horse off of the expensive stuff and onto maintenance supplements. I also had Ginisee on Corta-Flx after Adequan and she did great on that, too.
Though I haven't had Gin on Adequan for quite a few years now (no need, she's retired!), my vet has a generic that is much more affordable that he claims works just the same. Might want to look into a generic if you are worried about the expense.