To me, working in a private school in China is akin to working in a Sales and Marketing position in the West.

If you can 'put up the numbers' that the company wants then yes, you'll be successful.

The reason for this is that most private schools expend more time and effort on sales and marketing than they do on academic quality. To argue about whether this is right or wrong is pointless. It's just a fact!

Anyone considering coming to work in private school in China should consider that
1. The schools primary aim is to make money
2. A foreign teacher is a hefty investment by the school and if that investment doesn't pay off then the Chinese management will have no problem with cutting you lose (refer to point 1.)
3. If you are on a year long contract then you can be sure that they'll want you to start performing straight away. Take anything a school says to you about 'developing you as a teacher' with a large pinch of salt because they're not going to pay you 3-4 times the average salary of a Chinese worker for you to attend training sessions (refer to points 1 & 2)
4. Chinese management very rarely encourage creativity, independence and decision making in their staff. They want it done their way and their way only. If you can't handle that then again you'll be gone

I've met plenty of people who have worked at private schools for shorter periods (1-2years) and enjoyed it because they were able to stomach the above and fit in with what the school wants. If you can't then don't bother taking a job at a private school in China.