And now to the decisive argument for us: a new building today will hardly have a higher underfloor heating temperature of 23-24 degrees. 3 minutes of significantly warmer shower water should warm up the tiles quite quickly as well.
Unless you are a cold shower person, but then the question of heating hardly arises.
We were advised against it both by the screed layer and the sanitation expert. And yes, after a minute of showering, the floor is clearly warmer from the warm shower water than in the areas with underfloor heating.