Work other company on days off

Part of my contract that I can’t work for anyone else, driving or any other employment, other than voluntary work.

I’m on a 4 on/4 off pattern but occasionally do a 5th shift if

a) I can be arsed

b) It fits in with my home life and plans

OR

c) it’s all gone massively wrong, as it does sometimes, and I’m caught out of hours.

I at least know it’s appreciated where I am and is a favour “in the bank” plus the extra cash doesn’t hurt.

As already said - if they pay enough just do an extra day for the firm your with.

If the pay isn’t enough - explain that you want to do a bit extra elsewhere and see if you can come to an arrangement.