I was thinking more along the lines of early game upgrading and specifically, having to send weak heavy chariots and horses into tight spots to raise gold for knight upgrades. The same can be said of upgrading to tanks as you mentioned. It seems circular to me as well. I was, and still am, decrying the absurdity of having to war with upgradable units (and risk them being destroyed) in order to get the gold for upgrading. I played one test game with Shaka and was very short funding, and another with Pericles in which I had no trouble what-so-ever. Perhaps I was overreacting based on upgrading early Zulu heavy chariot corps to knight corps.