> It's terrible for scheduling conference calls. Instead of just converting timezones, you have to remember what a reasonable time of day is in each locality.
Sure, you still have to remember a time difference or negotiate back and forth. That part is the same amount of work. But you avoid a bunch of failure cases:
* Person from a large country with one official timezone (e.g. China) assumes that when the guy in New York says "10AM my time" that means the same as when the guy in San Francisco does.
* Weekly call at 10AM New York time, person from elsewhere in the world assumes it's going to be at the same time this week as last week, but it isn't because US DST changed on a different week from everyone else's.
* Both people misremember what the offset between their timezones is, think they've agreed on a time, neither notices until the call happens.
The solution to China making the crazy decision to have a single timezone or DST being an unnecessary complication isn't to get rid of timezones, it's for everyone to use them properly (i.e. no DST, everyone uses the correct geographical timezone (with adjustments if only a small part of a state or country is in a different timezones )).
Sure, you still have to remember a time difference or negotiate back and forth. That part is the same amount of work. But you avoid a bunch of failure cases:
* Person from a large country with one official timezone (e.g. China) assumes that when the guy in New York says "10AM my time" that means the same as when the guy in San Francisco does. * Weekly call at 10AM New York time, person from elsewhere in the world assumes it's going to be at the same time this week as last week, but it isn't because US DST changed on a different week from everyone else's. * Both people misremember what the offset between their timezones is, think they've agreed on a time, neither notices until the call happens.