Aim for a front corner when you hit off the backwall
I used to play with somebody who hit between 20 and 30 shots per match off the backwall.
Not out of necessity but because he chose to.
The problem was that because he didn’t need to, he had more time and better position than most players do when doing it and consequently was very good at them.
When you hit the ball off the backwall try to aim it so that it goes into the opposite frontwall corner.
Due to the spin of the ball (don’t worry you don’t have to try to hit any spin) when it hits the frontwall it will almost always go parallel to the sidewall.
So if you can make it hit the frontwall as close to the sidewall as possible, it’s actually possible to make it hard for your opponent.
Now, I fully realize that it’s easy for me to type these words but it’s much harder to do because if you are hitting it off the backwall then it must be a last ditch attempt to keep the rally going.
But as I keep saying: Hit every shot with intention.
Next time you get on court, try it and see what happens, you might be surprised.