hi hope i can help, i sub contract for the council and your right with what you say, ideally you shouldnt tile and grout in the same day, letalone in the same hrs, but the problem is you get paid same as site work, by pre meter ( finished ), so if you only put on 4 (m2) thats £40 so most tilers try fit 2 / 3 jobs in , in a day. slap and dash , slap and dash not the best work in the world but thats what some councils and contractors require and as long as they ll take the blame if something goes wrong then whos to argue . dont get me wrong i know theres a few people out there who this will upset and yes we know its not the correct way to tile but every building site in the uk does this and most councils, hospitals, and most big companys do it this way . i personally tell the council that ill provide the materials and only use powered adhesive that way i know that the adhesive will set even if its grouted.