Training

About training, I think its more useful during campaigns because they tend to have more concentrated and stronger enemies than in the conquests. In campaigns the health regeneration for gold and food is useful; there's never a need to use health packs in the campaigns. Many times it can be an ace in the hole.

For conquests I think the damage reduction is more important. You can see it especially when AI spam is trying to kill a 5 star general; the damage reduction of a flat -10 makes a big difference fighting single formation militia than a general on
a good unit. In conquests, the hard hitting units are more spread out over the map and a longer period of time passes making high nobility more useful.

Sometimes your artillery general gets stuck in a bad situation and training is critical. In Final Battle I always pit Sakurako on dbl heavy art vs. Davout. They both have help from surrounding forces but Sakurako can train 3 times while Davout can't at all. This makes a big difference.

I alomost never train Cav or Victoria either.