Not for skulls, a big skull blob for the most part always counted as a single match+2.
Now i can’t say for sure that there weren’t time periods inbetween when this was different but i know for sure it has been this way and openly acknowledged to work that way years back.
Edit: An older thread about this behaviour: https://community.gemsofwar.com/t/a-psa-involving-bone-dragon-and-warlord-4/13467