I've noticed that there is an order you can give to your units called "Check".
However, the tutorial doesn't explain what it is and I can't really tell what it does.
What is this for, and when should I use it?
I believe this forces your unit to look in that specific direction without necessarily aiming down the sight or decreasing his movement speed. It's a momentary glance so he will engage targets in that direction, then continue on hustling at full speed.