Thanks. 10 has been my favorite distance, since if I jog it at 7:30 pace it's around 75 minutes long or if I go quicker it's a little over an hour yet doesn't leave me wiped.
I'm thinking of improving easy day length before the long run - my workout days are about 3 or 10 apiece (depending if it's double threshold or speed), but my easy days are short. So if I can build them up I can cap it at 13 comfortably every week.