Depending on the jam and your ranking in the jam you should expect a little bit more traffic than without being in that jam. Also, as far as I understand it, many jams require the games specifically be made for them. So please do not just spam your game in jams that are unrelated. But if you do find a perfect jam for your game and you want to still be connected to that jam in a year, why not submit it.
And while I am not much into this jamming, I believe jams to simply showcase or bundle your games are not the type of jams that are intended by the concept. It is a jamming session, is it not? And the creative thing jammed together is games, instead of music or whatever.