Yeah I've been thinking about that, either make it so you can click runners to issue a return command, which is kinda cool but maybe too active for the game. Or something like you said, where if they already have a decent haul (mainly aritfacts or mithril) and are close to the stash, they return. But at the same time it's kinda funny/chaotic and part of the game to watch the silly dwarves do these silly maneuvers lol. We'll see.