my old boss did it himself once pretty easily.
the key is ensuring continuity throughout before tiling over.
i know it seems obvious but if you have 2 diff trades just doing their thing
i've seen a project where they had to remove the tiles b/c it didn't work.
also don't cheap out on dead zones. i recall when i was house hunting a few homes threw in heat in the kitchen and bathroom, and the dead zones can instantly be felt, warm and toasty tile and then bam, cold tile. just left a bad taste in my mouth....well, my feet actually.