I usually try to avoid the manned checkout at the supermarket in favour of the self service one
Why do you prefer the self service checkout?
It allows me to get done faster so I can go home and enjoy my groceries.
The self service check out at the grocery store can be very convenient, especially is you are in a hurry. I think it's smart choice if you're looking to check out quickly and get home and enjoy your groceries.
True that
It's sounds like you're well aware of how beneficial they are. It's good that you feel comfortable using them.