How consistent should icons be in sizing?

New to UX and confused about size consistency.

I know icons that belong in the same group are supposed to have the same visual weight, but what if there's different groups of icons on the same page or different icons on different pages...how consistent should their sizing be? Are they all supposed to have the same visual weight? As you can see below, my icons have varying heights, but of multiples of 4. Is this OK?