My default move is to map the L3 and R3 clicks to two of them. (I even unmap the actual stick clicks sometimes because I click them by accident a lot.)

I also find it useful in games where the situation changes and A B X & Y completely change what they do. Like if a game is mostly exploring but sometimes in a car/plane/spaceship/whatever, I’ll map the back buttons and use them when I’m in the secondary situation. (There’s lots of other examples of games that temporarily switch genres on you here and there and using the back buttons helps me remember the controls.)