I think there is some confusion here on re-used ideas, and the familar routines most episodes have.
All the banter with Compo and Nora in the mornings, Clegg and Howard, Foggy and the stranger, trips to the cafe etc - all deliberately made to seem the same.
Clegg's bad driving, buying old cars, messing about in water etc - again deliberately re-used from time to time - it's these things that make LOTSW.
Most of the time the show is clearly trying to be the same every week.
But actual re-used plots - quite rare really considering there's 295 shows. I suppose Uncle of the Bride and There Goes the Groom are similar - yet very different as well, so I wouldn't count these.