Never experienced focus issues or anything like that BUT I did one time process 120 that had been sitting in my c330 for months - after firing off a few BS frames at the end to finish the roll.
While loading the film (Hewes) this particular roll was pretty much impossible to spool at some point - as it kept binding and spoiling the rest of the load. I finally had to just man handle that portion of the film to get it to play nicely (hands sweating - all of that). After processing guess which frames were the most trashed? The ones right around where I shot the first finish-it frames. Amazingly the rest of the film was alright but what I took away from it is that if it's been in the camera to let it sit in finished rolled on the spool form for atleast some time before processing as that portion of the film had definitely taken up a curve as a result of sitting.
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.