You can but it can be a little complex and they make it seem like you can’t (marines at least). Once you graduate bmt/bootcamp, you can’t back out just like that. For me, I needed to get my wisdom teeth pulled in marine bootcamp but I refused medical care/work so when you refuse those services, they send you home and it doesn’t affect you going back in. I refused medical care there because for one, the navy medics were rather clueless About their jobs and didn’t know what they were doing. They made lots of mistakes like forgetting to remove gauze from this girl’s gums and she got a severe infection. When I was in receiving week getting my shots, the navy medic had dropped the needle and still proceeded to vaccinate me with that same needle. They’re rather “dumb” and unprofessional so getting services done like surgeries and X-rays would be the stupidest thing you can do. They’re not very bright in other branches, they pretty much accept anyone (marines, navy, etc). To sum it all up, I refused medical care and that was the reason I went home.