According to Chinese media, US carriers going through SCS is just for shows but underneath the water there were alot of confrontation between PLAN submarines and USN submarine around the water Southwest of Taiwan, near Dongsha island. It's the most strategic spot because it watching over the entrance into SCS from bashi channel between Taiwan and Philippines. Any US forces coming in will transit that area. For the past years and currently both side subs are hunting each other underneath.
Submarines showdown will be the deciding factor between PLAN and USN in SCS
093b is alot more important than 054a, 056. Overbuilding those surface ships is kind of pointless especially US cranking out alot of AshM Lasrm.
I don't think so or at least the PLAN doesn't think so. PLAN is disadvantaged going against USN sub to sub with their noisier subs, hence the best counter to that would be ASW surface vessels. This is leveraging PLAN's strength in surface ship technology and production. Remember that a sub, no matter how quiet, has no counter against active sonar. This is why the VDS is so important.
Y-8's won't be going to specific spots at a specific time unless the USN subs themselves might have been detected and the Y-8s might be performing simulated attacks against the subs.
Back from 2000 to 2012, there was a massive growth spurt in the number of PLAN submarines but since 2012, that shift to ASW vessels and there should be a strong reason behind it.