In the past, there was no computer remote trading. All customers' trading orders were reported to the seats of futures companies by telephone, and traders tapped into the trading terminal. In this way, traders can never leave their seats. If the transaction starts at 9 am and ends at 1 1:30, they can't go to the toilet.

Therefore, some exchanges (Zhengzhou Exchange did not rest in the past) added 15 minutes to facilitate traders to go to the toilet.

As for the argument that it is unreasonable to let traders rest, traders can close their positions if they want to rest (ultra-short-term traders), and long-term traders don't care about the convenience of those few minutes. Now it's all self-service transactions, but this tradition has been preserved.