My driveway is to the point where I need to invest some $ into it. It's about .3 mile long and mostly flat, but does have one spot where there's a decent incline. Last year I bought a land plane and used that a few times to help resurrect the gravel that was already there. I'm to the point now that I need to buy more gravel or get asphalt millings. Is there any reason to use gravel and not millings?