I'd rather say the reason is because Shandong is simply not ready yet. It's built from scratch, it has perhaps some significant changes to some of its internals and it simply needs to be tested and retested. It may need months, not weeks of various work done to it after every one of these test runs. The hole process is quite normal to take this long, even with the navies with much more experience with carriers.
CV17 Shandong is now at "shake down" stage, it will spend a lot more time at berth than CV16 Liaoning. Once the shake down is completed we will see her spend as much time at sea as Liaoning.
Two 055 at Qingdao is quite a bonanza. Obviously its either in service or some advanced trials. New trials procedure is that PLAN takes over and does the trials at some point.