Story telling time...
I believe in rotation, balancing & alignment, that go as a 1,2,3 & as important in maintaining your tires to get the best from them.
Some may know, some not. Your rear tires act to give stability (staggered are bigger), especially when braking on a wet surface.
Let"s say you have equal size tyres, they may be worn, the front looks worst than the back & you decide to put the new tires in the front(which many tyre shops will do so), your new tyres will easily disperse water easily, but the back the half-worn rears will be floating while trying to cut thru water (no stability).
The water will literally lift the worn rear tires off the road & your car could possible spin off, it happened to me once a long long time ago, but not my time
, so managed to pull it back straight after swinging the aft/back twice (left & right). That was a near miss for me, so after that i always changed all 4 at 1 go or the same time, never 2 at a time anymore.