I do a lot of laundry. When I discover the unmatched socks, they go into a small basket nearby. The next time I run the white load through (or the color load for colored socks), I add the mismatched socks to it. Usually the mate will be found this way, and it isn't another chore of going through a large amount of unmatched socks.
Ok, I know what you meant but I couldn't help but laugh thinking about all those lonely mateless socks bravely going into the washer to rescue their mates. How romantic! =(^.^)=