Built-in autosave feature (for the TE version).

This will significantly prolong the game when facing neutral creatures. I usually have 3-7 battles a day starting from day 1. But here, there will clearly be difficult battles. This means the game will be continuous and will take 2-3 times longer.

Believe me, if such a feature were implemented, the hero wouldn't be able to withstand 3-7 battles every day starting from day 1... Your army will be significantly reduced on the first ranged unit or fast infantry, and so on.
More likely, there will be a maximum of 1-2 battles a day, and a desire to just survive until Monday.
By the way, this should strengthen the role of Mage Heroes.