I'll be significantly cleaner than average I expect... I don't like cases, but a long time ago, circa when shiny black plastic was making its way in to touch screen phone design for the first time, a friend and I discovered if you keep your phone in a microfiber bag (like some sunglasses come with, particularly Oakleys we bought together at the time) it effectively cleans itself in your pocket. I still do, and I cycle those out and clean the bag once a year or so, or if it falls on the ground or gets something spilled on it. I have more now from different sets of sunglasses, laser goggles, etc.

I also happen to work in a clean room where you're expected to wipe anything you bring in, including phone, laptop, etc., with isopropanol-soaked wipes before entering so that's like disinfecting and taking off the oil every day or every other day.

No one else I know ever cleans their phone beyond wiping it with a shirt or something when the oil & smudges becomes too noticeable.