Wood/Clay/Iron:
(level x amount)
7x3, 10x1 : build bonus building, upgrade levels 2&3 to +15%
8x3, 10x1: build 20% bonus upgrade
9x3, 10x1: build 25% bonus upgrade.
Wheat:
5x2, 6x4: Build mill bonus +5%
6x6: Mill level 2 / 10%
7x6: Mill level 3 / 15%
8x6: Mill level 4&5 / 25%
8x5, 10x1: Bakery lvl 1-2 +10% (in addition to Mill)
9x5, 10x1, Bakery level 3
10x6: The guide said bakery level 4&5 are so inefficient you may as well settle a new town and level all it's wheat fields up. So stop at level 3 and level 10 wheats.