Wyverns

The bottom line is that battles of moderate difficulty (strong neutrals, and sometimes even the enemy's army) are completed with MUCH fewer losses, or even without any losses at all:D

That's correct. But only Paoka can be resurrected; others simply die without a chance of being revived. And the percentage of "consumed" health doesn't inspire much optimism – 20%. That is, to resurrect one Paoka normally (when any hero other than Shakarrukat), in other words, 120 health, you need to consume 600 health. And 600 health is 6 Paladins, 60 Archers, 3 Emerald Dragons, 40 Stalkers, etc. In any scenario, many of them will not be resurrected, which is unlikely to change the outcome of the battle, even if only one Paoka remains at the end (although, I agree, it's often better not to risk it, but the Battle of the Day can play a decisive role).

the number of uses is limited only by the number of corpses on the battlefield

Yes, and also by the Paoka's not very high initiative. And by the enemy hero's magical abilities.