A little bit of info that could be useful for new SSN build rates. US Newport news, which builds Virginia class, has quite a small hall for final assembly, but at the same time, it's easily definable it's likely all that's done there, just the final assembly. So it could be quite comparable to the Chinese production procedure. Unlike using the GD's Groton building halls or the British hall for Astute assembly (where it seems whole sections are made right there in the same hall)
Anyway, Newport news's hall is 129 by 93 meters. It has two slipways. While the submarine build list has occasionally "laid down" date of the next submarine coming after the "launch" date of the previous sub, in more instances that's not the case. Yet, when looking at the imagery of subs they made, it becomes (almost) apparent that indeed they ARE alternating building subs in one slipway, then another. So even though the laid down date may seem to leave some room before launch, it is very likely there is still some preparatory work needed, which indeed interferes with two subs being made in the same slipway in a given amount of time.
So basically, even though Newport news launched subs in:
2005, 2007, 2009, 2010, 2012, 2014, 2016, 2017, 2018 and 2020, they launched them from alternating slipways and building berths.
Initial subs took 3 years from laid down to being launched, block II and later subs took roughly year and a half. (of a note, GD's yard obviously has a different building procedure as they take the very same Virginia class sub from laying down to launching subs just one year)
But as written before, being laid down is obviously not the start of the assembly procedure. At least some months seem to be required, from launching one boat, to preparing the berth to start assembling new modules.
So, IF Virgina and it's building process at Newport News would be a point of comparison, true time for one slipway to eject a new submarine would likely be around 2 years when the procedure is familiar. And possibly 3 or 3.5 years for the initial subs, when the procedure is new and has to be learnt. Indeed, when one looks at time between launches for alternating subs at NN, that time is always 2 to 3 years. So 2 years is possible, but it may not be possible to drop the construction below that limit.
While the mentioned hall at Newport news has 4 set of tracks in total, two for each half of the building, only one half of the building hall is used per one submarine. 47 meters by 129 meters.
Using the Huludao new hall for comparison, it has 3 sections. Each of those sections has 2 set of tracks. And each section is 44 by 288 meters.
In NN building it is likely that one set of tracks into each building spot is used for either for workers and machinery, or for bringing in and furnishing modules not yet mated with the rest of the sub, and the rest of the sub is one the other set of tracks,
at Huludao, It's likely the one out of two set of tracks for each building site (out of 3 sites in total) is for work/furbishing/getting new empty modules. And parallel to that there is the track where two subs, each in different set of completeness, is positioned.
So when one sub is moved out of the hall, the sub behind it moves up a bit, and the new set of workers, which previously finished up the previous sub, works on it. It's sort of/kind of a mini pulsed line, where one set of workers and machinery stays stationary and receives a new sub to do the work they're most proficient at.
Still, a sub needs a certain amount of time to be finished. If NN is the comparison point, then subs at huludao, with all 3 sections of the hall working, will initially need 3.5 years to launch, with that dropping to 2 years after a decade of experience. There is likely room for 3 or so subs being worked on at the same time in one third of the entire hall, with two set of tracks. Of course, not all 3 are in the same state of completion. When one is almost finished, the third one likely has just several modules in the hall, with other modules not even arriving before the first sub launches and allows space for the whole pulse line to move a bit.
Anyway. Assuming whole building hall with 3 sections has each section launch a sub in 3.5 years in the beginning and launch a sub in 2 years after years of experience: in the first 3.5 years one might be looking at roughly 9 submarines launched. In next 3 years another 9, in the following 2.5 years another 9 and in the next 2 years another 9. That's 36 submarines in 11 years from the first launch.
That may be the best performance case scenario. It's always possible actual production rates due to unforeseen events complicate the learning curve. Still, with that new building hall with two more sections being built - overall production rate from all 5 sections may eventually not only meet 36 subs in 11 years but go over it, by some margin.