Tactics for playing against a Necromancer.

Then I don't quite understand why take a skill if you're not going to get the maximum benefit from it for the desired progression.

Why? What kind of question is that? The maximum benefit will be achieved at level twenty (and I'm not going to play that long), and my goal is to level up a combat-ready hero as quickly as possible, knowing approximately what my abilities will be in terms of development by the end of the second week of the game (this is the minimum time and level of progression for me to prepare for an attack; the time may vary depending on the map), and then by the end of the 3rd-4th week, finish off the enemy.
I have progression priorities, for example, Magic Attraction in Education, Plague Tent in Machines, Fire Wars in Summoning, etc. In practice, to prepare a strong rushing hero, I need level 15-16!