It is not only China Southern it is a China wide problem. Lasting six years in China is extremely ridden with pitfalls and high risk all along the path. The initial medical failure rate is now about 35% and recurrent failure rates are 5-10%. This coupled with astronaut style check rides, punishment for small mistakes and FOQA (QAR) items like long landings beyond 2000 feet, high or low rotation rates on takeoff, hard landings above 1.6 whether yours or your Copilots, speed brakes extended with falpas greater than 5, any GPWS warnings like sink rate, bank angle or any altitude deviations greater than 300 feet and numerous other items besides the medicals make it a long hard road to stay in China. It is certainly not for the faint of heart or those inflexible or those who complain at all as they will rapidly get rid of you through numerous draconian management styles. Come here and make as much as you can as fast as you can but don't think this is a long term job both for your sanity and your ability to stay flying here.