Timesinks frequently fail to deter players from setting goals as much as they deter them from actually achieving them. And any time your players set a goal that they have to give up on, the odds of them quitting altogether have risen significantly.
Carrots are supposed to keep horses running. Some games treat their carrots like they're made of gold, or as if they fear their horse won't want carrots anymore if they give them out more than once a week. Actually, carrots are cheap as hell and horses can't eat enough of them.
XI is one such game with lots of land to cover and a stingy rider.