Been a while since I played the game, but in all translations I was confused why you'd want to build 12 spawning pools.

If I remember correctly, that building was for enabling creation of zerglings and other units in hatcheries (and also for researching upgrades) - but one building was enough to unlock those units in all hatcheries; and it did not produce any units itself, so building more of them wouldn't increase your unit output either.

You could in theory built several of them to research multiple upgrades in parallel, but there were only like 3 possible upgrades anyway, so it would make sense to build 12 of them.

The only reason I could think of would be as a sort of redundancy, so you can keep building zerglings even if the enemy destroys some of the pools. But 12 also seems excessive for that.

So what exactly was the motivation here?

Sorry if I'm talking rubbish here, as I said, it's been a while.