What kind of magic do you like the most?

Okay, let's take a Necromancer as an example. It's definitely necessary to choose one of the magic schools. Definitely prioritize education. If Logistics becomes available, definitely take it. Next: it's highly desirable to enhance your attacks; it will work well considering the Necromancer's fairly high average damage and the elemental skill. If Logistics doesn't appear, you should at least take Luck for the same reason as Attack (plus, when developing towards Chaos, you get a "lucky mage"). One slot remains. You can take a very useful spell that will allow you to cast spells much more often and reduce mana problems, or a second school. Which, in general, isn't entirely irreplaceable compared to the first: it turns out that you still use spells from one school more often, and the others are "secondary." If we want to take both schools and the spell, we have to give up Luck or even Logistics! And no matter how strong our mage is, his troops play a far from insignificant role in battle, and movement speed on the map is even more important, because you need to develop faster than the enemy... No, you can take two magic schools, but it will inevitably be detrimental to something, while with one school, you can manage without any particular problems.