Periodically I put my rulers on edge to see if are warped or curved and I store them nicely and flat. I drop stuff a lot, partly because of my lack of depth perception I think. But my iron gets dropped, my coffee cups get dropped and my rulers get dropped and shatter often enough to be replaced.
We each have a slightly different hand to our cutting whether we are completely perpendicular to the ruler or slope in or out. I prefer to use all of one brand of rulers on each project if I can, I think some are better used on the line and some are next to the line.