Not quite chaos but it can certainly be an inconvenience depending on circumstances.

My major client has offices in Eastern Europe, Russia and Southern Africa.

The Eastern European office is usually 7 hours ahead except when it is 6 for those few days when the switch to summer/winter time doesn't align with North America.

Russia has the same time all year and is 8 hours ahead or 7 depending on whether we are standard or daylight saving.

Africa is either 7, 6 or 5 hours ahead because they spring forward when we fall back but the changes aren't on the same date.

Now try and get everyone on a conference call at the same time. At least they don't have an office in Newfoundland where everything is a half hour later.