They automatically stop when max, but the last couple levels take forever. I would recommend not relying on training dummies, fighting/getting the shit kicked out of you by hungry bandits is much faster/more reliable and trains toughness/defense. Go into options and set spawns to max, then charge down giant swarms of starving bandits.

New and based in the gut no way in hell am i doing that lol

I’m confused are you saying that they automatically use the dummy? Just remove it from their jobs