The Lifespan of an LP?

Usually after about 20 plays or so I start hearing some small pops. They are still negligible. Maybe after 50 or so, the play noise is readily noticeable, and that’s the time for ultrasonic cleaning. After cleaning, it gets a little bit better, but the small pops do not completely go away, which means the damage is permanently done. However, I would still rate those records as Mint- or VG+++.

The damage is mostly due to badly setup cartridges, old/damaged cartridges, and playing dirty/damaged records. So, if your cartridge set up is near perfect and if you clean records each time you play with needles in good condition, the record will remain in VG+ condition after hundreds of play.

I don't do ultrasonic clean or spin clean every time. 
I do carbon fiber brush clean each play.
However, after 50 times or so play after a few years without spin/ultrasonic clean, I start hearing more pops. With a regular brush clean I can easily see tiny dusts entrenched in record groove. After ultrasonic clean, the record plays with less pops, and usually sound better.
There is a chance that the records were damaged due to misalignment, because sometimes the cartridge force changes and need readjustment.

I purchased a newly retipped Ortofon MC20 super a few months ago, and I still hear pops on those new albums I purchased several years ago. I have about 10 cartridges used in rotation with four arms, but maybe I need another brand new cartridge to experiment with. 
By the way, even after over 50 times of play, the sound quality remains almost the same. Only a few more small pops. The fact though is, every time a record is played, the record wears out, however small may it be, and it will be noticeable sooner or later depending upon how the record is cared and the turntable is set up.