Last week my partner & I were in Xi'an for 7 days - both on SIMBA's Senior Plan. I'd 0.21GB balance after the trip; partner's was 0.99GB balance - I didn't surf as much as when I'm in SG though.
I'd another SIMBA's PrePaid $12 with 18GB for China etc which I gave to a friend, on the same tour, to use - she used nearly 4GB.
Most times we were allocated 4G by CTC (I presume China Telecom). 99.9% was good, only on one occasion all SIMBA's subscribers on tour had no signals, even trying airplane mode on/off, change APN, on/off phone, manual choosing other Telcos (which was rejected) etc.
Finally it worked by switching in phone's settings (Preferred Network Type) to focus on 4G without option for 5G. It was only a small hiccup. Much later when I switched back to have Auto 5G the issue didn't arise again
Signal coverage was very good, whether high up in the hills, deep down in the vallies, deep undergrounds, highways etc...
Added:
Didn't use hotel WiFi at all as Google, Whatsapp etc cannot be accessed.