Indefinitely for all practical purposes as long as you: (1) keep the record and stylus clean, (2) don't play it with a worn stylus, (3) and keep tracking force low (2 grams or preferably less). Records I purchased in 1967 and played with a spherical Pickering cartridge in a Garrard record changer still sound pretty good (which tracked closer to 3 grams a bit too heavy) when played back with today's more sophisticated tip geometries, especially because they ride in a different part of the groove than the old spherical tip. Records I purchased from 1978 on and played with a Shure V15 types III, IV, or V with elliptical or micro ridge tips sound as good as ever with my latest Jasco stylus or with my latest Shure M97xE. The effective tracking force with the Shure V15's was 1 gram. I'm sure that some of my favorites were played many hundreds of times. Not only that, until around 2000 I played them on a Techniques SL 1650 record changer in auto that I purchased in 1978 and still use today. Yes, I stacked 6 records at a time for over 20 years and never had a record degrade. Now, since the changer function has stopped working, I use the same turntable as a semi-automatic.
The Lifespan of an LP?
How many times can one play a new vinyl lp before the sound noticeably degrades? For the purpose of the exercise, assume one takes decent care of the record and has a properly set up and maintained, good quality deck and stylus. My system has been taking quantum leaps in quality over the last three years and I find myself buying more mint and near-mint vintage records on Discogs and audiophile remastered records from MoFi etc. Thanks!