Dirty_Player
Auto-translated
P.S. I'm not sure. It feels like native heroes appear more often. (If anyone has accurate information, please share it). For example, for Necropolis, it is not uncommon to have 5 native heroes on the first level.
So, the idea about native heroes being common is a myth.
P.S.: This data is for SoD. I don't think they changed anything in TE.