How hard do you focus on boss weaknesses?

I find myself super focusing most of my efforts on just trying to get stuff and passives for the weakness, and for example ignoring magic damage stuff, even with Duchess. Though I know stuff like carian grandeur hits like a truck.

So, how much do you usually focus on it, and how much do you go for other stuff that will bring the damage you need?

Note: I'm still pretty early in the game and my relics are kind of all over the place, so they don't really affect my builds that much. I'm mostly focusing on clearing Everdark Sovereigns and Balancers still.