Polaroid doesn't age particularly well. Color materials are prone to color shifts, and with both B&W and color the developing pods seem to dry out, so you're much more likely to get undeveloped corners with old Polaroid film. I'd recommend using it while it's fresh or within a year of going past date.
If you end up with old type 55 and have development problems, then the best solution is to shoot it as negative film, remove the neg in the darkroom, and process it like Panatomic-X. With 665 it's a little more complicated, because you would have to remove sheets from the pack as they were exposed (in a changing bag, for instance), without running the sheet through the roller.