of course with other strong navies joint exercises is better, but dosn't mean this is only way.
not only chinese navy, army, air force, they are all get nothing with other strong countries joint exerises, also, Western has been sanction of China for 60 years, but PLA still getting strong.
of course, if China got Western help, chinese military got double strong, not like some body said behind the world 20 years.
but PLA is still world power now.
also, in fact, there are no any strong countries would real help others become strong military power.