Very little chance
Yes. It's late.
Most IM and FM programs have already sent their invitations and have a short "waiting list" to work on during the next couple of weeks.
Am not saying that the chances are zero% you may still get interviews if you increase the number of applied programs but the chance is very low.
If you are going to step-down, I mean you'll apply to a lower profile programs then yes do it because this means that you will try a new groups of programs and that would certainly increase your chances. But if you just want to add more programs of the same type/specialty/level then I see there's very little chance that you are going to get an interview at this time.
Bottom line, if you have $1000 that you don't care about then give it a shot. Otherwise, I suggest you start working on improving your profile for the next year match.