Thank you for playing! Also thanks for bringing up the tension thing, in hindsight I guess some control explanations in the description would've helped.
If it helps now though, whenever any box is pulled too far for too long (~ 2 seconds), it will snap the tether. The only exceptions are when a heavy box is stuck in place (takes 4 seconds), when a heavy box is in the air, and when a light box is on the ground (both never break).