Paul,
I've always twisted any wires that I've worked with.
The exception would be the larger sizes and Aluminium wires.
One aspect of Electrical work here, that annoys me, is where two wires feed a Surface-mount MCB base on a Switch-board panel and the wires aren't twisted together.
It's not the shock aspect of replacing the base live, but if the wires are carrying any sort of load, it makes for a bit of sparking.
In my opinion, pre-twisting gives you a better connection between the wires and also lessens the likelihood of cutting into the strands of the wire with a terminal that only uses a screw to hold the wire strands in the terminal body.
