Another added element upon snooken's point, been to many school many different countries, spent >100K too.
Every school is typically structured with 1 or 2 head pilot in there, one who has above 10,000 hours of professional experience (generally own the school) and one who is just a really a good instructor (abide less experienced). and stay with the school because he is good and they therefore pay him well.
on top of that you get staff instructors that come and go and are generally mediocre at teaching. some are so bad that the role could get reversed and you will find yourself more competent in the right seat and on your toes prepared to correct the instructor mistakes on occasion.
Anyhow as a matter of business efficiency, every student will have to spend time with the staff instructors, and it's not necessarily bad, because every student has to learn the basic stuff like keeping a precise altitude and heading in straight and level flight. it does not take a star instructor to teach you that. Personally I qualify a bad school, one in which you spend your time craving to fly with the 1 or 2 head pilot, because they are the one that make the lesson worth 3 time a much learning, you will feel like they just have the key to unlock your progress as a pilot.
if you get really lucky you might find a school where due to their small scale they don't have staff instructor and will do all your training with the head pilot --> in that case go for it, you will never regret it.
it also alway help when someone in the school is also an examiner, good sign they know what they are teaching and are on track with what you should know