What is a reasonable length of time?

user1977

And how often they're used.

Okell

Crikey!  What are people doing with their pillowcases???

MyRealNameToo

Okell said:

Crikey!  What are people doing with their pillowcases???

You probably dont want to know, and it'd breach the rules of the forum anyway. 

Ours are certainly much older but we intentionally buy a heavy cotton or linen plus both washing machine and dryer have a bed linen function that stops them getting anywhere near as knotted and tangled so probably reduces the stress. 

Others may prefer a much lighter fabric which may well look more delicate etc but probably is actually more delicate too so won't age so well

the_lunatic_is_in_my_head

Okell said:

We're still using pillow cases that must be at least 10 if not 20 years old.

Is that unusual?

No it's not, picked up some from JL some 20 years ago and they are still going strong.