I've been doing a lot more wet rooms recently, a lot with ufh, what's people's thoughts on running the heat mat into the tray area too and round the trap etc
Some do, some don't. If you do, you will probably have to smooth tile adhesive over the cable on the former due to the gradient and SLC the rest. I have done both, but be mindful that as the former nears the drain it gets a lot thinner. This can cause heat issues with it giving off uneven temperatures in different areas.