This is the same on all new cleans. There are several reasons for things taking time in the beginning, you need to find plug sockets, you have to get used to the building where bins are, you are out to impress so you will carry out a full deep clean etc.
Don't worry a 3hr job to start will easily turn into 2 when you get into routine for example, on every visit you won't be cleaning behind the toilet, you won't do a full wash down of the tiles, you won't need to clean all of the kitchen cupboards etc etc, these are 'periodic' jobs, you will only do one of this kind of job once per week which will cut time. You will be surprised how much time you will save just getting used to the building and getting into a routine, I always tell my cleaners it takes about two weeks to get used to a site. As you get more experienced you will take on 'visual' cleaning where by you will spend your precious cleaning time cleaning the areas that are in need of cleaning and not vacuuming clean carpet or polishing dust free desks.
Good luck
Fox