I would be happy to wash those things between each guest but my water supply simply doesn't allow for that and I'd be running back and forth to the laundromat (which is expensive where I live- a load would cost me a quarter of what I charge per night for the room, not to mention gas and time) every few days.
As I only host single travelers who pretty much hit the beach every day and shower when they get home or right before bed, I don't think it necessary to wash the mattress pad or the blankets or duvet cover each time. And I do use top sheets, so the blanket and duvet don't come in contact with the guest's bodies.
I do, however, shake out those items and hang them out in the sun and fresh air for half a day between guests (easy to do if you live in a hot climate, not so easy if you don't or its raining).
If I had a guest who I perceived as not particularly clean, who smelled bad, or whose room smelled bad, I'd definitely wash those things before the next guest arrival.
Hotels most certainly do not wash those items between all guests. I read somewhere that the average was once a season. And that goes for "good" hotels as well.
