We have down comforters and down pillows. I wash them every other month on average. My oldest one is 12yo, I buy one or two new ones every couple years... but that's a money thing (like having extra blankets for guests). The 12-8yo ones are in as good a condition as the 2yo ones. I've lost ONE due to a feather explosion, but that was my own fault. I SAW the tiny rip before I tossed it in the machine, and I saw a few feathers in the machine before I put it in the dryer... but they just didn't click. My son was an infant, so it must have been sleep dep. Two braincells decided to rub together and get a spark JUST before I opened the dryer to reposition the comforter. POOOFT. It was like a down grenade! The entire room, and myself, covered in softly drifting snow by the time my brain turned on. Oopsies.
HERE'S MY CAVEAT ON DOWN:
My husband decided that he'd be helpful (yay!) and wash a couple of them a few years ago. I had to trash them. With down you have to reeeeeeally let them dry!!! Tennis balls in the dryer, and when you think they're dry (about 6 or 8 hours in), you dry them for another 3-4 hours.
When down doesn't fully dry, the feathers clump and a good 50% of the loft is lost... but that's not the major problem, just the major annoyance. The major problem is that if the feathers are damp.... they molder. I could never get them unmoldy again. If they're just not fully dry, you can rewash and dry and the loft returns. If they've moldered, there's the smell / danger of breathing mold all night long... and the loft NEVER returns.
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I do the couch every 6mo. I should probably do it more often, but that's how often I do it. I bought the kind that all the fabric zips off of the cushions, so it's really easy. Zip off, washing machine, dryer, zip on. I bought this kind on purpose after being sick and tired of using Murphey's Oil Soap on my old leather couch!!! The leather chairs I don't mind using Murphey's on, because I can do 1 chair in about an hour, and leave the rest for whenever I feel like it. The leather couch meant 3-4 hours of work, because it all had to be done at once!