try to complete the "absolute power" campaign in 6 weeks. If you manage to do it, please let me know.
Although, the last time I played single-player (Heroes 3), I completed an average map for 8 players in less than a month. But it wasn't a scenario map.
Now I understand your opinion: against a dumb AI, any powerful ability is an "overpowered" ability, especially the War Cry spell. But a smart opponent won't sit around with -5 base damage against a Necropolis faction.