Anyone can make up claims without providing evidence. That's lazy.These reasons are more credible for you only.
I provided evidence for my claim: the first Type 052D was also the fastest to go from launch to commissioning. Somewhat surprising that first of class would take the shortest amount of time in sea trials, if it's all about crew training and proficiency. But it's not outside the realm of plausible.
The two ships launched in 2016 took 39 months from launch to commissioning. What happened there? Ships prior to that were taking 27 to 33 months. The follow on ships took just 24 and 18 months respectively.
What is your evidence that sea trials alone explain the massive variation of 18 to 39 months from launch to commissioning?
How would you explain the variation at BIW from 10 months to 25 months from launch to commission? The ship that took 25 months of outfitting&trials was also one of the fastest ones to be launched (11 months).