If you mean applying EX, then S+G a few days later, then EX another few days later, I don't think so.
If you mean applying EX, letting it cure, then using S+G flollowed by another coat of EX right after, again, I don't think so.
If you use S+G to remove a coat of EX, you may get a bit more gloss, but your durability may be compromised.
These are just presumptions, though, as I haven't actually experimented with this myself.