Landings!
If you are paying for each landing or T&G then you are learning at the wrong place!
It is common practice forsome trainning providors to buy landing fee contracts at the airfields they are based at and then charge the student pilots at the full "visitor" rate. This is a nice little money maker.
As an instructor I have found that the number of landings before solo flight is usualy constant, however the number of hours to solo depends on the size of the circuit, those places with large circuits to avoid noise sensitive zones are likely to be more costly to fly at.