BlinnPhong vs Standard Light performance

Hi, I’m working on a game which is graphically very similar to civilization 6 (hexagonal map). I use several planes for terrain mesh and each plane has a diffuse and normal texture. So I was wondering should I use Lambert/BlinnPhong or Standard lighting on the terrain? Visually I don’t see much difference except from the fresnel on grazing angles but I have a locked camera rotation so not even the fresnel is visible. Would I benefit from a perfrormance perspective by using those simpler lighting models? The rest of the game (units/buildings etc) uses standard lighting

What is the question? If a simpler shader model would be faster? Yes. Enough to matter? It depends.

But I think it is more of an art style question than a performance question. I think completely disregarding speculars and going all lambert is fine and might make the game look cleaner.