How many plays can you get out of a good record?

Now we have the relatively low cost technology to make transparent digital copies off vinyl re-play.  Someone should do this with some newly acquired high quality LPs, wait 10-20 years, keep track of the use, and then play the vinyl and compare it to how it sounded 10-20 years prior.  That is the only way to make a subjective judgement.  I suppose you could shrink the time element by playing the same LP over and over again and compare digital recordings done before vs after. There may be formal studies where a test LP with test tones is played repeatedly, so as to detect loss of HF or bass frequencies.  I don't have a good digital recorder, even if I cared about this issue.

A lifetime for sure. After that it's out of my hands.

The trick is to have so many records that you can't play any single copy too often.

Perspective is a funny thing. Time was, I would have cringed at 1.8 gram tracking.

If the pressing is reasonably good, records are clean and your turntable set-up is correct I wouldn’t worry much, though I too treat every record with LAST.

It is not recommended to play records more often than once every 24 hours, vinyl needs time to recover.

I also have two/three copies of my most favorite records.

It is more likely that you will accidentally damage a record than wear it out.