Serious question: wear spots on irons

Just how much golf, and or how dirty, do your clubs have to constantly be, to develop a wear spot on the face? I play twice a week, and go to the range for 100ish balls another 2 times per week. I’m not great, but I consistently see the general spot where dirty range balls hit, but I’m not even remotely close to developing an actual wear spot. I clean my shit off and it’s like nothing ever happened. They are 2019 p790s too, so going on 6 years old.