I've been here over 8 months and had never changed out a blade for cutting vinyl. I don't suspect we use it "that much" compared to others to ware it down that much, but some colors cut great like the white....while a few others like Royal, don't cut "as well". Takes more effort to peel it up.
I think it's cutting ok, just maybe the characteristics of some colors maybe?
Do some colors just cut better than others? They are all the same manufacturer. So I'm also thinking AGE. If that were the case, then perhaps it vinyl might be more brittle than the other newer vinyls.
Colors can be odd. Like some ink colors print easier than others. I might be reaching, but say a Royal, contains more minerals that might make it more difficult for a smooth cut. For inks, the Cyan ink particles are more oblong shaped and is often why Cyan tends to pubg up more in the screen (I'm told by an ink manufacturer at one time).