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.