shaders vs decals better performance?

I sometimes like to give my materials a dirty or wet effect i see people using decals and some using shaders which one is better for performance?

in my humble opinion,

if you want the whole material, or big part of it wet… inside the material is often the best choice.
For splashes of fluid hitting surfaces, decals might be better.

If its inside the shader, there is no additional drawcall, while… (as far as I know) decals do create an additional drawcall.

ok good to know, recently also noticed that you need high poly surfaces to have good looking shaders so i think i found an answer