Control the center of the gaming table, that is your wargaming tactica for the next game.
(Unless you are playing an air/space/sea game…)
All wargames are played on a finite gaming area, be it gaming table, hex map, or board- there is a limit to where you can go. Likewise, most units in the game, once they are on the table they can not voluntarily leave the table. If you gen get a blob of models or units in the center of the table, and hold it- this physically cuts off the mid zone of the table- limiting the areas of movement that your opponent will have- pushing them and keeping them in the deployment zone.
It funnels opposing units to the sides of the table, where they are further blocked by the table edges- allowing you to focus your fire on the funneling units to the side.
So what units should you be pushing up the center? Something that has the staying power to shut down the center of the table for a few turns, so you can influence the flow of opposing models and focus fire/focus your shooting dice on needed units.
Staying power either means something really tough in terms of wounds, durability, etc. or really numerous if weak in wounds/durability.
Taking a mass of models focuses on quantity being it’s own quality. Shut down the center. Concentrate shooting dice on the sides.