Battlefield size in Heroes 5.

Most monsters can be reached in two turns. You can withstand one shot from a level 20 hero, but then he won't be able to shoot anymore:)

I'm aware of that. That's why I mentioned potions of immortality (it would be interesting if they were hard to obtain and/or appeared in the shop once a week, for example) and very large armies.
It's just that the idea about the 4th game, it would be nice to move "Magic Resistance" to some less useful skill ("Nobility", for example).

And what are the tactics in the 5th game?

I can't tell you anything about that. I haven't played the beta. I'm completely relying on your opinion and your worldview. Maybe you're right. That's exactly why I didn't write about the 5th game, because I don't know. I'm just questioning the idea that a large map is a good thing.
There's an opinion that the square grid was made only for 4-cell monsters, because they would look awkward on hexagons... As you remember, in the 3rd game, 2-cell monsters were always in a horizontal position, possibly due to the 2D graphics. I see hexagons like this:
1. Single-cell monsters.
2. Two-cell monsters. They can be placed at an angle, not just horizontally.
3. Four-cell monsters. A big question mark.
4. Seven-cell monsters. They are too big.

We have 7 stacks on each side!!!!!!!! What are 8 attack possibilities for?

What about summoning creatures?
But I completely agree with you, 8 attack possibilities aren't very interesting, and they aren't needed.
I have some questions for you, as someone who played the beta:
Is it possible to surround a single-cell monster with 4 of the same type?
Because it seems that the 8th cell is mainly for retreating?