Alaska is close enough, it's wide enough to cover 4 timezones

http://www.alaska.org/how-big-is-alaska

Granted most people live in the space of 1 or 2.

People say this all the time. But if you look at a population density map of China, you realize that the vast majority of people live within the natural GMT+8 range, and the western region is very sparsely populated.

For some context in case anyone was curious, my calculations suggest that ~3/4 of China = ~1 billion people are in the main band of GMT+8 (or slightly east), ~1/4 = ~300 million people are naturally in GMT+7, and only ~2% = 25 million people are at GMT+6 (or slightly west).

The province of Sichuan (capital Chengdu), with a population of ~80 million people, is the most prominent province naturally one time zone west of Beijing.

As far as I remember it's not even an appropriate TZ for Beijing. More like central China time.

How does this affect people living on Western borders in China ? Do they have really long days ?

I imagine they get up when the sun rises (about 9am their time) and go home / retire before the sun sets (about 9pm).

Their days are only "long" in the sense that they probably go to bed after midnight. They still have the same average number of hours in a day as anyone at their latitude and altitude.

That is why all the over-complicated time systems are dumb. You don't actually give yourself more time. You over-complicate reality to suit cultural norms like "the sun rises at 6am" despite the fact most people will grow up never moving that far from where they are born. If the sun rose at 1am people would sleep from 4 to 12, not try to force a standard time schedule of 6am sunrises on an entire population. They already don't - people get up generally around their sunrises everywhere on Earth - they just change clocks to make that sunrise always be around 6am.

Time zones and DST are an accommodation for moving across time zones so no matter where you go you can use the clock as a reference to solar noon, except in the dozens / hundreds of instances where you cannot. The consequence is that the complicated system is hard to track, makes cross-zone communication and scheduling a nightmare, and causes legitimate accidents when people do not know where the date lines are, when the times change, how they change (I think there is a stretch of Russian border where you can go 3 hours forward and backward in time in about 100km).

Or any country, since timezones only have a 1 hour granularity. If you're in Edinburgh (same longitude as Plymouth) this is quite noticable. Be interesting to see the consequences of hyper-local timezones where the sun is always over your head at 12 noon. With modern computing it should be possible to have your watch adjust as you drive east-west ...

Time zones can have any granularity desired. Most are 1 hour, several are 30 minutes (including in India and Australia), and a few are 45 minutes (in New Zealand, for example). There’s no rule though about granularity though.

From my experience working with date/time I don't think there are any rules at all.

New Zealand's timezones are full hours, not 45 minutes. You might be thinking of Nepal? (Picky - your broader point is of course right.)

I think the poster is refering to Chatham Islands timezone[1].

[1] https://www.timeanddate.com/time/zone/new-zealand/chatham-is...

Nope, OP is correct - the Chatham Islands are GMT + 12 hours 45 minutes.

There are actually a few 30 minute and I think even 15 minute timezones.

And then we need to track lat/longs for every timestamp!

"Says here you arrived at 1.33pm! You were meant to be there at 1.30pm!" "But Sir, look, it was 57 miles east so I was early!"

Most countries agree to use a 1-hour division, but not all. Iran's offset, for example, is +3:30.