Originally Posted by jiejie

The part I bolded is variable. Only some locations limit to the greater city limits. As a counterexample, Guangzhou's 72 hour TWOV allows the entire Guangdong province. Information I have is that Xiamen's 72 hour TWOV, established in 2015, allows all of Fujian province, which includes Wuyishan. However, I don't know of any data points where anyone on TWOV has ventured this far.

However, IMO, the time is better spent at the Hakka tulou near Yongding, and in the Quanzhou area, both of which are a lot closer to Xiamen city. Most foreigners find Wuyishan to be quite meh.