Another way to say it is, understand the quantity of resources you put into a weapon, understand what that produces, and understand what/how much usage you'll have for it.

Do you know what investing in an SR assault gets you, and for how much?
Do you know what investing in Adramelech bow (or any other Rush (L) only weapon) gets you, and for how much?
Do you know what investing in Illuyanka gun (or any other Defender/Rush weapon) gets you, and for how much?