Tonguez
A suffusion of yellow
In my family's home rew RPG, characters are more like wargame units.
It in Necromancers work on both sides as Heroes can be attached to our command Troops, Elites, or Mounts.
So the zombies attacks are rolled and move with the Necromancers. So their turn is fast.
If the Necromancer detaches zombies off their Troop unit and must follow Troop rules. So you need to be high level or use lesser zombies.
Well we did allow my cousin's Warlock to detach a single inp into an Elite Troop once. it devolved to degenerate play fast
Heh, I'm doing a similar thing inspired by Dynasty Warriors where Units are treated as dormant terrain hazards which the DM can deploy on a battlefield immobile until they triggered by PC or Enemy passing through on their way to an actual objective.
PC Commanders get a feat to attach a Unit as a 'Body Guard Squad' who can move with the PC and who the PC can Command via a bonus action to use an attack or a formation/tactic.
So for Dynasty Warriors type play you might choose a Spearman Squad that gets to use a Spear Thrust attack, a Spear Wall formation (10 x 30 wall of spears) doing 3d10 damage.
Modifying that for Necromancers "Zombie pack" I'd give them a slam attack and a grasping swarm formation (knock down target).
Anyway by treating Units as Terrain hazards triggered by PC action (or bonus action) the focus remains on the PCs not on creatures to be worried about.