Why are there 3 periods in hockey?

Answer 1

I guess because this has been the traditional format of the game. The game is played at such speed and there is so much physical contact that players need two rest periods. I think that some years ago there was an experiment in pre-season games to see if two 30-minute halves would be practical but the idea was ruled out.

Answer 2

There are three periods in hockey to allow for breaks and rest periods during the game. Each period typically lasts 20 minutes, and the breaks between periods allow teams to regroup, make adjustments, and give players a chance to rest and rehydrate. The intermissions also provide an opportunity for TV commercials and other game-related activities.