Don't get me started on how much powder residue can build up in a pistol before you need to completely disassemble it, clean, grease, and put it back together. This is a photo taken Sunday of my 75B bullseye match gun frame that I used to win the local January match with on Saturday of last weekend. I missed the usual December frame cleaning. Still no malfunctions and no change in trigger pull. Note, this is NOT lint and NOT dirt or sand buildup, those are different. This is all powder residue from the .22 Kadet slide, plus a little 9mm residue thrown in. I've added some light oil periodically but don't ever try to clean it between disassembly because I don't want to push any surface grunge in between the moving parts. What you see just sits there and doesn't hurt a thing. The contact points remain lubricated.
My P-09/07 pistols look "bad" too but the buildup on a centerfire only gun is so slow compared to a .22 that I don't worry about them at all. Add oil, shoot.
Bores, chambers, breech faces, extractors, barrel ramps, slide surfaces, barrel bushings, magazines are different. They get cleaned and lubed very often. But not the no load small movement frame parts.
Joe