Can I endorse the recommendation from Roamer808, based on my own experience.
If the tiles are not put down on a full bed of grout they will come loose eventually, maybe even crack.
If this is in a kitchen or bathoom area you can end up with water under the tiles and they will come loose.
Tilers like to leave hollows as the tiles are easier to level and place - that way they are much easier to "work".
Something an interior designer or architect should be all over tilers for is to get them to "equalize" their tiles.
Tilers can fail to assess the tile module against the wall or floor width and this exacerbates two issues.
Very few rooms are perfectly square and leaving a narrow on one side tile exacerbates this problem.
Starting with a whole tile in the corner, you seldom get a full unit at the other side of the room.
The worst is a sliver tile left over - its almost impossible to cut much less than 1/8 of a tile...
It can be better to even out the tiles to leave say 1/2 or 1/3 tiles to form a border of partials around a field of whole tiles...
This is why in classical buildings you will often see a border tile surrounding the whole tiles and then the "odd" tiles running out to the walls.
This "centres" the tiles on the space and allows you to choose which axis you want to align the border to, or if you want to ignore the surrounding walls totally.
Sometimes in a totally assymetrical room, or one with a lot of alcoves, you may choose to do a primary form in the center as a focus and let the tiles outside the borders "run out" to the walls.
Just some tips and tricks with tiles...
ONQ.
[broken link removed]
All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.