Heres some pics of restaraunt tile.
I sub'd for a cruddy floor covering contractor who was working with an even cruddy'r builder.
The floor was un-level. Lots of low and hi spots. And the drains sloped unevenly.
I asked my contact guy if he wanted me to, I'd lay a 1/2" mud job to straighten out the floor.
He told me "just do the best you can do with the tile".
So I had to fudge thin-set here and there.
I should have gotten a before pic. So you could see the disaster.
The bath was a pleasure to work on though.