I have adjusted the back-/frontfocus setting in my camera for different lenses.
Now I am wondering if I have to readjust the lenses regularly? Does the back-/frontfocus for a lens change much over time?
No. Well, I've never seen it happen.
If it does, I would suspect an imminent mechanical failure.
What I did see once is front or back focusing change between focus-distances. In that case the lens focuses well at one distance but is off at another. Since I've only see it once, it may a defect rather than tolerance error.