Karachi is 10 hours ahead of Houston

There is no standard 8-to-6 overlap. Someone joins early or late.

A 10-hour difference puts Houston and Karachi out of sync — when one team is mid-morning, the other is fast asleep. Consider rotating the inconvenience: one week Houston takes the early call, the next week Karachi does. Finally, Houston observes daylight saving and Karachi doesn't, so this window shifts by an hour for part of the year — recheck it each spring and autumn.