Does lowering through rap rings or chains cause significant wear? I live in an area with established crags, but not many locals. When anchors need replacing, there's a small group of folks around who have the knowledge, equipment and desire to do so. It seems to me that encouraging folks to lower would cause the anchors to wear out sooner. Is it best to double rope rappel if you are the last climber and cleaning the climb?
When I was a child, such a long, long, long time ago, two to four times a year at grade school they'd blast the siren and all us kids would hop under our desks and put our heads between our knees. Supposedly the exercise was to prep us for the imminent launch of Russian nukes (or were they Chinese?), but really it was to instill a deep groinal fear of what could happen to us if we didn't all go along with the doctrine of the day (DOD). As the French philosopher Denis Diderot said, Man will never be free until the last king is strangled with the entrails of the last priest.
The DOD that's got everybody by the grapes today is this absurd fear of wearing out the anchors. Where did this come from? Of course lowering through a station will wear it out. Soooo? When the links or biners or hooks or whatever it is that's up there get worn replace them! This little chore doesn't take any skillful skills or cost much. The problem arises when people are too lazy, too cheap or too ignorant to do the work. In that case, they should quit climbing and take up bass fishing, where you can just sit on your tub and excel.
Since you asked about lowering versus rappelling, I assume you are sport climbing, and using the anchors to lower to the ground. Typically, sport anchors are rigged with either steel, threadable chain, steel hooks or fixed carabiners, which are probably aluminum but should be steel because steel lasts just about forever. I also imagine that you are talking about lowering after working a route, since everyone knows that you don't work a route with the rope threaded through the anchor, which does cause unnecessary wear and tear. (To work or TR a route, clip the anchor with your draws, and let them take the abuse. Replace your quickdraws when they become grooved.)
Lower, rather than rap, on a sport route because it frees both of your hands for cleaning the draws on the way down, and lets you tram into the rope.
You do need to recognize the rare stations that are rigged for rappelling only. These you'll mostly find at trad areas or atop sport routes put up by Luddites who insist on weaving web tat through the gear and capping it with a flimsy aluminum descending ring, or using a tiny chain through which the rope will barely fit. In those situations, lowering just isn't prudent. Next!