Well if you only have one mine then your workers will get bored faster. And when all your workers get bored, the game is over.
not if you manage to have at least one worker active.
but i tried a few times, lol. and it puts the last created worker at bored, exactly 1 second before you can buy a fresh one, while 2 are already on bored mode. even if i use two mines. its exact. i need 2 seconds more :)
so, if that timer is adjusted by a second or 2 or 5, then it could be a game achievement and people can have a second go.
why would you prohibit that? :) ( since it is so precise i assume it is on purpose)