Cubdriver

Do you mean "privately" as in with a local instructor who owns an airplane? Or a small, privately based FBO type school? Please clarify what you mean. Fixed Base Operators (FBOs) are also called "flying schools" and many of them are privately owned. Perhaps you mean a large university, pilot mill such as AllATPs, or Embry Riddle, or UND. Not sure what you mean by flight school and by the term "privately".

But if you mean that you wonder how good larger schools are in comparison to say, an FBO in your home town or an individual working the same airport, then yes they can be fine but they are more likely to show inconsistency in their teaching than larger schools are. The advantage of larger schools is they have a more structured, standardized curriculum. Large schools often operate under FAR Part 141 rules which requires an approved curriculum. Many students benefit from the additional structure offered by a Part 141 school and are able to progress faster than with a small, Part 61 school. There is a more homogenous style of teaching at a large school. The advantage of a large school is mainly that your are not as likely to receive a substandard instructor.

Where I teach we have a standardized syllabus. We offer the student a chance to work with multiple instructors during their course of study, and we require them to use a different instructor than the usual one for all of their progress checks. We have a uniform, FAA-approved curriculum which produces good pilots that have flown with a variety of instructors.

However, if a smaller, private school or individual is known to be high quality or you have a strong desire to avoid a large school for some reason, then it may be advantageous to stay close to home and use the smaller school. The main advantage is in the convenience. Things being equal, I would prefer a Part 141 school over a smaller one like an FBO, unless I had some reason to think the small school has particularly good instructors. There are definitley some examples of the latter to be found, Kerschner's school and Herb Pello's school come to mind.