The last few times I have taken the PVG-HKG flight, the late-afternoon/early-evening flights have been delayed departure ex-PVG (specifically, I am talking about CX 369 and CX 381 services). This was due to the late arrival of the incoming aircraft from HKG-PVG On the other two times leaving PVG and SHA, respectively, in the late-morning/early-afternoon, those flights have departed on time.

If OP is planning CX 381 --> CX 408, and CX 381 is significantly delayed, you will miss the CX 408 connection; the transit time is 60 min between these two flights.