It's pretty expensive though. I think that's why a lot of vets try food changes first.
My golden retriever has had hot spots throughout his life, at times almost continuously (we'd treat it, he'd be healed for a couple of weeks, and then get another one.)
Four or so years ago, I got tired of the perpetual vet visits and we did go to a specialist vet in Pittsburgh for testing. They gave us some treatments that our regular vet hadn't prescribed or suggested, and did the skin prick tests. I think they also sent his blood out to check for food allergies, but I forget now. What they ultimately wanted to do was allergy shots, but we decided against it for time and money reasons. We kept managing his spots as they occurred but were able to manage them at home some of the time with the topical medicines they prescribed.
Oddly enough, he's 8.5 now and has only gotten 2 spots in the past 7 months, both of which we've caught early and been able to treat at home without antibiotics or steroids. I don't know if it's because he's older and spends more time lying around the house, less time rolling around outside, or because we moved to a different house and installed a whole-house humidifier (not for him, but maybe he benefited from it) or what. We're down to a hypoallergenic bath every couple of weeks (instead of every few days), and no Apoquel, though we still feed grain-free, chicken-free food.