Ah, I thought the minor stat boosts could be subtracted off of the overall gain you'd get after beating a boss, but I wasn't sure. That means you should only fight random battles if you feel like it yourself. Sure, you get money and items, but as far as I remember, I hardly ever used money for many things. You can find most of the elements in the game, including the healing ones, so you don't have to use consumable healing spells. Upgrading to new weapons and armor is also something I don't do all that often, and it's not expensive anyway. There's also many pieces of armor to be found in dungeons or by stealing from bosses.