All good recommendations here. I recently did mine..... 22x24, Pex tied to the mesh, they lifted the mesh with the notches in their shovels during the pour. Since they pretty much always stood where they could see the Pex (ahead of the pour) they never really got close to the Pex when they lifted the mesh. The foreman constantly reminded them to shovel very slowly, and only long the direction of the tubing runs. I had a pressure test gauge hooked up and watched it like a hawk, a very nervous hawk. Lol. The only close call was the truck dropping its chute right on one of the Pex tubes, but it didn't make a mark.
I also took pictures and measurements of my layout right before the pour. Sure, it might shift a little, but if I know it is 12" apart, and I drill right in the middle..... I figure I'm safe. I already tweaked the layout for bolting down a lift, one interior sill plate, and the column that sits on the thickened area of the slab.