I honestly don't remember the last time I replaced my sheets but I had to throw the last set out because the material simply ripped open on all sides, very odd. And now my bedspread seems to be following suit, I don't know how long I've had this thing either but about a week ago I realized one spot on my side of the bed was getting threadbare, and now the thread has given way to a hole in the middle of the cover, so now I've got to get that replaced as well. Kind of odd because that's the first time I ever saw that happen with either the sheets or the spread.

Often enough.

As needed. We recently bought 2 new blankets as the old one was in pretty poor shape, most of my sheets were either bought at yard sales or at walmart once when they had a really good sale. The mattress cover was bought new when we bought the bed a few years ago.

I usually replace the fitted sheet when it gets so thin I can read thru it or it one day rips. I use the same sheet set, washing it once a week with my blue laundry. The life span of laundered things is usually about a year or 52 washings. So, I guess every year or whenever it wears out.

I have 5 sets of sheets so I am constantly rotating, when I get bored of one set I replace it and throw the other out. I have about 10 different bed comforters so I switch off on those and like the sheets when I get bored of one I get rid of it and replace it with a new one. Yes I know I am anal.

"As needed"

Pretty much like everyone else. Whenever they need it. It just depends on the quality from set to set.

I guess when I can see they are starting to wear thin.

I probably buy a new set twice a year, and throw one out once a year.