Regarding resting the razor, I'm inclined to think it's a myth in part if not the whole.

Magpie's right about steel being elastic, and there may be a measure of "return" gained from allowing a razor to rest. However, the blunting that's caused by your whiskers as you shave is too severe considering the edge's thickness to return completely on its own. That's why we have to strop between shaves, even if we let that razor rest a day or a week. Dent a soda can and you might be able to pop it back out to original shape but usually the points of that dent will leave a deformation. Now consider that a can is thicker than the leading edge of the razor, so that fine edge will be permanently distorted by shaving.

All that said, it's a wonderful myth for those who wish to sell or buy more razors. "No sir, one razor simply won't do! You have to let that razor edge rest at least 24, no I'd say 48 hours before you shave with it again. That's why we're offering this one time special deal! Buy one razor, get the second one 25% off!"

JMHO

Peace,
Jim