Are all the Zon builds taking years longer than promised, or is it just a lucky few who are repeatedly bumped to the back of the line?
I don't believe it's all Zon builds, not even with the 2020 calamities (pandemic, CA wildfires). We have to keep in mind that unhappy customers are quicker to post negative comments than happy ones are to share positive ones.
Two data points I can speak to personally: I ordered mine in mid-2017, and got it 9 months later, just one month over ETA -- no complaint from me, especially given the long waits that I'd learned about. However a friend ordered his around the same time: it took two full years to arrive, and same as others with long waits, he was extremely unhappy with the lack of communication from the shop.
Here on TB, Angus, basschanges, mrgittleman, and now Rumblefisher have experienced / are still experiencing extreme delays: 3+ years. MaidenBass waited two years before understandably losing his patience. Pretty sure there have been others, and I've only been following Zon for 3 years or so. However some TBers besides me have received their orders approximately on time. We tend to remember the bad news, and overlook the good because it's expected.
Overall, my hunch is that Zon goes for the lowest hanging fruit in order to deliver as many on-time orders as possible. If there's a hitch with someone's build, it'll be shelved until the shop manages to find some catch-up time: after all, that order is already late, the customer is already unhappy, so the goal is to minimize the overall number of unhappy customers. Again, just my hunch that's solely based on what I've read here on TB.