You'll find that the vast majority of instructors at any school are hour building to go onto the airlines. Given the amount of money they have spent can you blame them, it's their ultimate aim. They don't want to carry on instructing for the rest of their career.
In any case not all instructors are hours building, if you are planning on doing your training as quickly as possible, as some do, you shouldn't have a problem. If you are only doing a couple of lessons a month and planning to take your time there is no reason why you shouldn't request a career instructor, LAC have a few.
The majority of people don't experience problems with continuity as far as instructors go. As I said earlier if you have issues with any school it's better to speak to the people in charge and express any concerns. At the end of the day, we, the paying customers, are paying their wages. Where would they be without us? They are there to help us!!