There is a chap that calls with videos. Part of the routine is that after my wife has chosen it, I am called to check whether she has seen it before. If I am not around, she very often watches the same one two or three times but seems resigned to it and enjoys them any way.

I used to get books on a regular basis for a chap from a local library. He had a good idea for ensuring that he did not get books he had already read. He would put in little 'tick', in pencil, on page 88 of every one that he had read. If I saw a book that I thought he might like, I would turn to page 88. Fell down when they had more than one copy of popular titles, but it worked well otherwise.