Walkthroughs of standard maps, focusing on SPEED.

It's obvious that digging up heroes is a good strategy.

On the islands? Where we have only 1 ship and enough gold for at most one hero... He'll start and sail off, I don't see any important role for a secondary hero, except for the army.

Added after 11 hours 46 minutes
On the 1000 Islands map, it's actually easier to complete the map in 5 days playing as the orange faction. It's closer to sail. And the island is richer, so it's really possible to dig up a hero there.
I installed a tree-finding program, it's a good program, and I quickly found the navigation with its help.