The legendary longest Go game.

There is an allusion of "failing in science of chess watching":

During the Jin Dynasty, there was a man named Wang Zhi. One day, he went to the stone house in Xin 'an County to collect firewood. I saw a child playing Go on a big stone by the stream, so I put the chopping axe on the ground by the stream and stayed there to watch. After watching it for a long time, the young man said, "It's time for you to go home." When the king got up to get the axe, he saw that the handle of the axe was rotten and the sharpened axe was rusty. The king is strange. When I got home, I found that great changes had taken place in my hometown. No one recognized him, and several old people said it was hundreds of years ago. It turned out that the king's stone mountain fell into a fairyland and met a fairy. One day in fairyland is a hundred years on earth. Later, later generations took "rotten ke" as an alias for Go.

As for the current international competitions, there is generally a time limit, and the longest is only 6 hours. But fast chess is becoming a trend more and more!