You can do it. But as a current intern, you learn all you need to know as you go. I never did a med sub-I, and I don't feel like I'm missing anything, and at least at my medical school, med students were fairly restricted as far as what they were allowed to do, no order writing, every note cosigned. If you can truly act on an intern level, write orders, have some measure of management over patients, sure, go for it. But I have more colleagues wishing they had done that easy radiology elective or creative writing elective, rather than brush up on medicine with the AI/sub-I in medicine that they did in 4th year.
my 2 cents
zen76