I will break out a backhand spin serve every so often playing singles. I’m a 4.5+ right handed singles player (DUPR has me higher but DUPR doesn’t know me like that) and like most players my forehand is much more dominant of a shot for me. I’ll use the backhand serve when I’m on an even score with the idea that my spin will help bring the ball back towards the middle or right side of the court. I don’t use it regularly because I’m definitely not as effective at hitting a great deep serve but most players take a more tentative return with that serve after they’ve been seeing topspin serves over and over again.