A wide timezone gap is workable. What breaks people is an unstated expectation of constant availability.
Agree the overlap explicitly
Two or three fixed hours, written down, used for anything that needs conversation. Outside it, async only. Vagueness here is what turns into 11pm calls.
Hand over in writing
End your day with a note: what state things are in, what is blocked, what the next person can pick up. This is the mechanism that makes a twelve-hour gap a feature rather than a delay.
Rotate the inconvenience
If one region always takes the early call, resentment builds. Rotating is a small courtesy with a large effect on how long people stay.
Common questions
How much timezone overlap is needed?
Two to four hours is usually enough if the team writes things down properly.
Is a twelve-hour gap workable?
Yes, with a genuine handover habit. It is a documentation problem, not a scheduling one.