I suspect we'll see a bit more of this now that the US is considering sending ships and planes within the 12 mile limit of China's reclaimed islands, which to be honest is quite a potentially hazardous action. It's quite different to the ADIZ situation where China could respond to whatever level of military force they wanted to -- in this situation OTOH, it is a direct challenge to sovereignty over those islands and given both countries interpret the status of those islands differently there may well be a risk of PLA military posturing if not military force to evict US vessels from the boundary as a matter of PRC principle.
I wonder what kind of ships both sides will size each other up with.
More importantly, I wonder if there will be any response to US planes, such as a limited kind of ADIZ. I don't think the PLAAF and PLANAF in the region are quite able to do persistent patrols out to the entirety of the SCS yet, although I think JH-7/As, flankers and J-10s with refuelling could make a good shot for it. Either way I can't see the PLA accepting US surveillance flights within their island's airspace sitting down.