I seem to recall I had a "check-up" once back when I still lived in Bangkok. I think it was when visa extensions were still done at Soi Suan Phlu, so that was, what, 20 years ago? The physician just signed a form, nothing was really checked and I paid a couple hundred baht. I had a physical exam five or six years ago, but it had nothing to do with my extensions. I've decided there's no reason for me to get physical check-ups. If I'm not sick enough to be in the hospital, I would just incur more expenses.