Now and again I check and retighten the cage bolts. Loose bolts and tall, heavy bottles overstress the frame. At the top of my 1,5L I have an extra velcro strap to keep the bottle from moving
very good point to bring up, I would add the importance of using loctite on bolts for heavy water bottle cages.
But as you wisely brought up, regularly checking bolt tightness of all your bikes bolts anyway, that's the key thing.
On the other end of this, I have once stupidly overtightened a rack bolt and damaged the threads of the bolt insert thing in an aluminium frame.