Best of HeroesWorld

As far as I've read reports on this template, I gathered that external dwellings of level 6 are commonplace, probably as much as level 7 ones.
In total, there should probably be no less than 3 external dwellings of that level and a few more of levels 1-3.

Well, basically yes. A normal total of external dwellings starts somewhere around 20 (roughly 2-3 high-level ones and a ton of low-level ones).

And having your native secondary skill here is a mega-lucky break.

Debatable. You might not have enough tempo for building in the 1st week. And in the case of CoD, not enough money either. Essentially, having your native secondary skill gives a normal bonus to the following towns:
- Barb (actually enables fitting bears and birds into the tempo)
- Necr (only need to fit vampires, you can even get by without the Citadel)
- Dungeon (portal + Troglodytes)
For the rest, the native secondary skill is no more than a gold mine + 2 external dwellings. Good, but clearly not a mega-lucky break.

A mega-lucky break is having native Center... can't be countered :).