I have matress protectors, pillow protectors and plain duvet covers, then bedsheets, pillowcases and coloured/patterned duvet covers. Duvets and pillow go outside 'naked' on first suitable spring day and regularly until wet Autumn, occasional airing late in year depending on weather. My machine would not like heavy load, take duvets to laundry when special offer, is two for one or second half price. Pillows binned as necessary but protectors washed regularly certainly lengthen pillow life. AC go off with anything they can so sometimes get to replace pillows sooner than usual. Take my mattresses outside to air when a very good spell of weather, also vacuum them with a pair of tights over the vacuum head(has it got a name?) when I change the protectors. I don't like replacing items if I can prolong life by care. Also clear washing machine and tumble drier filters regularly. Loathe dusting. John Lewis sale for pillows.