I'm not really sure, but my feeling tells me we are seeing in fact two different units - one for the NTC (Liaoning) at Huangdicun and one for the STC (Shandong) at Lingshui. Today, both are maybe not yet fully established (at least at Lingshui) and are based together with sharing mixed deployments, but for the future I assume all 01-24 + 30-35 are for the NTC (= 30 minus those crashed/lost/written off or about 28 J-15s), while all 6x/7x-serials are for the SCS, so that we will eventually see from no. 60 up to no. 87/88.
Why there is a cut or break between no. 24 and 30 - aka 6 more J-15s - I cannot explain ...
Maybe anyone of you has a more reasonable theory?