Emperor’s Emporium of Empowering Improvements

Speed.

The very definition of speed is its rate of change of its position with a respect to its frame of reference, and is a function of time. Or in a less fancy way, it went from there to here in this amount of time. Which within that definition is a number of concepts that are important in miniature gaming: position, frame of reference, and time.
Quick anecdote: a customer once came back from their first large Warhammer 40k tournament and I asked them how was it. The first response was Everyone used up all their fast attack slots.
Why is that? Well, position, frame of reference and time.
First, position. Position is basically where your models are on the table. The wrinkle of it though, are your units in the right position? Or can your units get into the right position? Position is always key, if your aren’t where you need to be in the game, then you will not get to perform the action you want.
What frame of reference is, is the action or actions you want to perform. This is basically what your unit can effect. Can I level my offensive action against the opposing unit? Does my unit have that objective covered? These are the frame of references that one is to ask of a unit every turn, and you only get there through positioning.
And then time, which is the turns that we play under and around. Everytime you sit across the table from your opponent, you both have agreed in principle to a finite amount of turns. Can I get into position when I need to? And can I get to my opponents units before they can get to mine? These questions answered gives your army a efficiency that helps you win the battle.
Back to the anecdote, the reason that players were using all their fast attack slots in the 40k tournament, is because classically the fast attack slot has the models with the most movement across the surface of the table. This is the most basic way to get to position, and change your frame of reference of the unit to a more favorable outcome. Move across the table fast, you do not waste turns getting to where your units need to be.
Every single turn is precious, you only have so many of them. Understanding that, speeding up your game plan, and your army can go a long way in a short time to reducing the effectiveness of your opponents army. Movement is not the only way to leverage your position into to the best frame of reference for your unit (Range is key also) but it helps out a lot. Next time you start to put a list down on paper, figure out how long the whole army will take to get across the surface. If its a little slow, swap something out to speed things up a little. Your opponent probably won’t like it.