Might need to have maybe two seperate options, one to always show and one to show only for selected units.
Use case scenarios would be to quickly check if you have any blind spots where defenses don't cover at a quick glance. Another would be to see engagement range of your mobile units when you plan on being in combat.
Another use case scenario would be if you have a turret building blueprint ready to be placed, you could see it's engagement range before placing so you can decide if it's a good spot to build it without having to build it first and then checking the range.
