I can certainly see why not to go in a yearly re-watch if you go for the whole thing!
Me? I can go and watch a single episode of any show just because something remind me of some little bit and I have to go and be sure I'm remembering well *laughs*
But I can go in a mad marathon, too, and watch complete long shows like BtVS, X-Files, or ST-TNG just because I miss them SO much!