My apartment is always tidy, but it's never 100% clean. Which doesn't mean that it's dirty, but I rarely ever clean the windows, dust off the furniture, or mop the floors. Usually, I only vacuum all spots that are easy to reach, and I immediately remove all clutter before it builds up. That makes sense to me. Scrubbing every corner with a toothbrush does not.
My windows are clean enough as long as they still let sufficient amounts of sunlight through. In my experience, it takes about 5-6 years until the light starts getting a little dim, so I only clean the windows in leap years. Dusting is an utterly pointless endeavour. If I frequently use a desk or table, it will remain dust free all by itself. And if I never use it, why would I care if it looks a little fuzzy? I also don't vacuum under furniture. I sit on the furniture, not under it, so I don't care about the evolutionary processes that might be going on in spaces that are too small for the cats to crawl into and start sneezing. I'm practical like that