I mention this because of my mother's crazy ideas about housekeeping (they included raking the carpet after vacuuming, to remove the marks the vacuum cleaner left). She thought soft furniture should be vacuumed inside and out at least once a week (well, until she had to pay market rate for it. My guess is she backed off at that point, because I never saw the woman she hired when I started babysitting do it. Who made $30 for what I'd been stuck doing for $2. Not an hour, mind you. And it took more than an hour.). I think that soft furniture should be vacuumed when I've lost enough stuff in the couch to make it worth digging for it.
Today, I found a cordless phone that had gone missing. Very exciting! Also the red ring from the stacker toy (altho to be fair, that was under the couch. Which I did not move, much less vacuum under). And may I also add how much I love my Miele vacuum.