I wasn't quite happy with some solutions on Fujian from the start, but IMHO, China should start working on second ship as soon as Fujian left the dock. China needs as many carriers as soon as possible, even with some flaws. So, if they need 2 years in dock and 2 years outside, that should be the tempo, at least for 2 or 3 CATOBARs, and during that time they should develop final version of nuclear carrier.
I also think that just one CATOBAR carrier is insufficient. And if China wants to increase the rate of pilot training and development of doctrines they should have built at least two of the Fujian type if not more. Nuclear supercarriers are supremely expensive, not just in acquisition costs but also maintenance. USS John F. Kennedy (CV-67) was a conventional supercarrier that the US operated for like 39 years. Which is perfectly respectable.
Everyone would agree that the PLAN will require additional CATOBAR carriers, but both of you are thinking on a scale that is a bit too short.
The question for the PLA, is whether it makes sense to pursue another CATOBAR carrier (whether 003 pattern or otherwise) without a pause, or with very little pause, after CV-18 Fujian.
Technological maturity is one reason why immediately going for a followup CATOBAR carrier after CV-18 may not be wise, after all it uses EM catapults and is a much larger and more capable ship than anything the Chinese naval shipbuilding industry has built before.
But it's also a matter of opportunity cost. CV-18 Fujian is not likely to enter service before 2025, and even then will take a couple of years to get fully ready for service. If they bought another carrier right after CV-18, it likely wouldn't enter service until 2027 and would also need additional time to get ready for service.
However, an additional carrier is also going to consume funds, crewing, and escorts, and time. Everyone seems to view the latter half of this decade as being a dangerous period in which the likelihood of conflict is heightened, which in turn means that having mature platforms with high readiness and best bang for buck is important. All of which is to say, buying a second CATOBAR carrier may result in a ship during that time which is unable to be properly combat ready and would only be drawing up valuable military, shipyard and monetary resources.
Or putting it simply -- perhaps the reason they haven't bought an additional CATOBAR carrier immediately after Fujian, is because they don't want to have another CATOBAR carrier that would only enter combat readiness in the end of the decade where it would be a suboptimal use of limited resources for a highly tense geostrategic environment, and that it only makes sense to do further CATOBAR procurement after that period if they project the geostrategic balance to be one that can become less risky and more in their favour.
Good procurement isn't just a matter of "more, as soon as possible" but rather buying the right things at the right time.