Whenever a tv show comes on that I have already seen I immediately switch channels, whilst my husband is quite happy to watch something again. "It's a waste of your life!" I cry, "watching something twice."
I think the same applies to most fiction. I definitely don't re-read thrillers, crime mysteries and the like. What's the point? If the whole aim is to keep you guessing 'whodunnit' then reading it again comes into my 'waste of your life' category. I actually know someone who reads the endings of thrillers before buying them, to make sure she is going to enjoy the book. That really baffles me.
I do read non-fiction over and over again as well as the occasional long novel. I am currently reading Penmarric by Susan Howatch. I know I've read it before but I don't remember a word so far!
No, in my opinion, there are so many books in the world that reading something twice is definitely a waste of your life!