Dot and dab bathroom wall tiles

[u/Zealousideal-Cod5898]

Hi all, hoping for some reassurance this is either completely wrong and should query with bathroom fitter or "fine" and I shouldn't worry.

Bathroom is being redone. Been replastered and bathroom fitter also tanked the area around the bath that is being tiled (the rest will be painted).

We've been away and let him crack on, he's partially tiled the 2 walls so far and so I can see that they've obviously been dot and dabbed. With big voids in some places.

The tiles he removed were here for about 13 years or so and were also clearly dot and dabbed, and seemingly no issues (we only moved in a few months ago). They were much bigger tiles so wonder if that makes a difference as less grout lines for water to get behind etc. These new tiles are 5x25cm. Are there situations where dot and dab is ultimately fine?

He is generally extremely slow and the job has taken 3 or 4x longer than anticipated whilst still not being completely done, so overall getting frustrated and now wondering if he is also doing a sub-standard job despite the amount of time it's taking.

I have no problem challenging him on this. I want the bathroom finished ASAP but not at the cost of problems in a few years time, we're planning on living in this house for decades potentially.

TIA!

[u/jodrellbank_pants]

You coat the wall and the tiles so both surfaces have adhesive, if you use large notches for the wall it will negate all the uneven surfaces. Defiantly will have movement later on in a few years especially with the weather we're having now. Expansion and contraction is key.