No. Each unit in Heroes 3 has a VALUE parameter!
It's not clear about hit points: they are a variable...
In short: how do you understand this?
In short, calculate your value and the value of the neutrals. Divide one by the other. If the result is greater than 2, then they will be in the same stack!
How do you calculate the strength of an army of crossbowmen (which specific numbers should be taken into account) and how do you calculate the strength of an army of angels (based on 9 angels or 6 + 3 archangels)?
These calculations are based on the formula, but I can't check them right now.
Of course, each monster has its own value, because each has a different number of hit points. Dirty, I'm not insisting on my correctness, but I always calculate it this way (although I always estimate it by eye, because it is not so important for online play).
If that were the case, then the Black Dragon would be considered stronger than the Archangel, but that's not the case... And the value of the Archangel is higher.