I have to disagree with you about upgrading peasants. Firstly, building the upgrade structure requires resources. Secondly, upgrading the peasants themselves also costs resources. Thirdly, upgrading peasants is a loss, as upgraded peasants don't generate income (and all losses are undesirable for players, as they need to upgrade troops, which requires a lot of money). Fourthly, it's better to upgrade peasants to archers if you're going to do anything with them at all. That's my opinion.