Racial ability: "Preparation".

Hmm... Why not? Unupgraded Angels aren't particularly powerful, and upgrading them is quite expensive. Therefore, if you're not aiming to amass huge armies of 10-30 level 7 creatures, this approach can be quite effective. A particularly useful method is to maximize the skill that reduces unit training costs and focus on the creatures your hero specializes in (archers, heavy infantry, or paladins). If your hero has a different specialization, you should base your decision on your financial situation. If you've captured a lot of gold mines and looted several Utopias, then knights and paladins can be the main backbone of your army. However, if you haven't had much luck with gold income from overseas, but your city and its loyal taxpayers provide a stable income, and you also have a good income from nearby lands, then the most reliable and optimal approach is to upgrade heavy infantry to inquisitors, thereby transforming slow, albeit formidable, warriors into a significant ranged force, and in large numbers. But if luck has passed you by, and your city is experiencing a serious crisis, and you're barely making ends meet, then there's no point in opening a training hall. Otherwise, when at least some money remains, you can train peasants to stop paying modest taxes, give them conquistador helmets and crossbows, and send them into battle. :)