Your Cybertronians-work-like-working-dogs headcanon is so good, accurate, and valid. But now…who to apply it to? There are so many bots and so many different ways to apply this.

Everybody. 
Much to the frustration of medics whose jobs include exertion when they need to not be doing things like running around on a busted leg. Medics probably keep a stock of Things To Do on hand to keep their patients from complaining even more.