Bathrooms here are frequently the most expensive rooms in the house, which makes how a repair is approached matter as much as the repair itself.
You may not need to open the tile
This is where real money is saved. Many valve repairs are reached through the existing trim plate or an access panel, and where genuine access is needed it is usually a small opening in an adjoining closet wall rather than the shower face. Before agreeing to a tear-out of stone or custom tile, ask whether the valve can be reached from behind.
Custom tile cannot be matched
Stone, custom glaze and imported tile are effectively irreplaceable once a run is discontinued. Working around them takes longer and is nearly always the right call.
Stiff or scalding valves
A shower that will not hold temperature usually has a worn cartridge. It degrades over months until someone gets scalded when a tap runs elsewhere. Replacing the cartridge restores control.
Ceiling stains below a bathroom
The pan, the drain connection, or grout letting water past the pan edge. Three different repairs, and identifying which before opening anything is the difference between a targeted fix and losing the bathroom.