Shenzhen is 13 hours ahead of Atlanta
There is no standard 8-to-6 overlap. Someone joins early or late.
Practically speaking, Atlanta and Shenzhen never share office hours; 13 hours of separation keeps their days apart. To talk live, someone has to flex: an early start in Atlanta can catch the tail end of the day in Shenzhen, or the other way round. Note the seasonal wrinkle: when Atlanta is on daylight saving and Shenzhen isn't, the gap between them grows or shrinks by an hour.