ASW – Alternative hero leveling.

What prevents developing an army in both?

You didn't understand the point. I'll explain with an example.

Let's say we have a Castle (our home base). And on the map, we encounter a Castle (Chaos version) and an Inferno. The hero levels up in Chaos.

In your case: building a second Castle + guild in it. In the classic version: building the second Castle for troops, building the Inferno for the guild. That is, almost the same thing.

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Most maps have difficult access to the second city.

I don't care about this majority, because I simply don't play on such boring maps. Of course, this is a subjective point of view, as is any opinion.