I postpone finishing things I enjoy a lot because I don't want them to end, but in the end I always regret the decision. All these games I saved before the final boss and never beat...
Life has taught me that the correct way to enjoy fiction is to watch/read/play it through the end and then feel bad about it being over. I think that heart rending feeling is precious in its own right, and if you'll just watch them later they'll lose the impact. It leaves you feeling numb.
I still have some specials, movies, OVAs from franchises I enjoyed about a decade ago (Ichigo Mashimaro and Kaleido Star most notably, but there are others) that I can't bring myself to watch, because that'd just mean they ended and that's that. At the same time, having waited all these years, I'm also scared I simply won't like them.
Finish stuff. I think you'll look back on it later and think it was the right thing to do. You can complain about me not doing as I preach but hey, I'm doing my best. It's not easy.