"Random" vs. "Fixed"

The map generator creates maps based on certain patterns, and there are quite a few of them. I even tried to study the patterns a long time ago and even drew some, but there are so many that I eventually gave up. And recently, I read reports from those who play on random maps, and the most interesting thing is that there are almost the same templates there, probably the most optimal and balanced ones. But I still don't understand how to make these templates generate on their own.