Hi all, I'm not sure that playing a vinyl record once is a good test of any theory about how spherical, elliptical and line contact styli affect the groove walls on a disc. The best case seems to be a lubricated stylus that is highly polished and is of a high quality hyper-elliptical shape (or better) with sufficient tracking force to hold the stylus in contact with both walls of the groove all the time, and equally. Once we get to a lubricated and highly polished spherical stylus (like a Denon 103), playing a new disc with sufficient tracking force and correct anti-skating, I think you'll find vinyl wear in the grooves goes way up (at least according to the NAB).
The reason for this seems to be that if an album is popular, and even if it is cleaned carefully every time between plays once per day, and even if the stylus is cleaned and lubed every time it is used for an album side, the "track" in the bottom of the grove caused by a spherical stylus can be seen clearly by about the 60th play. The disc of Iron Butterfly's "In a gada da vida" (?SP?) is played full length each time (it covers one side of the disc). We have a station here in Kansas City that often plays the Tangerine Dream album sides straight through, as well as M Olfield's Tubular Bells for their "New Age" show. Many many classical discs were played tris way. It is clear even with a standard microscope at 300x that there is a rippling effect of wear on the contact areas of these records.
As an AES member this problem was brought to our group 10-12 years years back. A radio station playing classical and other full-length-play albums was finding many albums unavailable on CD. These albums were also difficult to source on vinyl. The cost of maintaining a music library at a fastidious station was substantial. We had the station use calibrated Stereohedron Stanton cartridges whenever possible (681 S). The records in question seemed to last 3x to 4x times as long, before noise became objectionable due to the contact "track" that formed after as few as 60-70 plays using the Denon 103R catridge (also calibrated for Radio Station use). We (AES members) went in and chose the best of the remaining best turntables and arms. We set them up properly, and installed the cartridges ourselves. The problem was eventually solved (the high cost of replacement vinyl) by burning all these discs to CD once in a while and automating the shows.
But the problem is still there. The lubricants in the vinyl itself may "burn off" and then under-surface lubricants may re-mix with the fast melting vinyl (I prefer the view that the vinyl only softens, not fully melts). But eventually this built-in lubricant inside the vinyl formulation is gone. This is most obvious in discs made of 1/2 crushed vinyl and 1/2 new vinyl. It is obvious when viewing the grooves after a while, that the crushed vinyl particles are "showing thru" like cobblestones will eventually show thru when a thin layer of blacktop is put over them to produce a smoother ride in a car.
So play a new disc once and check for groove wear. Since my college minor was statistics I then suggest this test sequence; play it 10 times and check for wear. Use three discs; one with a spherical stylus, one with an elliptical stylus and one with a line contact stylus. Then check after 30 plays, then 60, then 100, then 150, then 225 plays and so on with a maximum of 1721 plays (if there is no visible creation of a new contact wear track in the groove bottom after 1721 plays, there is no need for further tests.), and compare how fast the track/noise wear occurs at the bottom of the groove. The spherical will always be worst, but the elliptical will only be useful for about 25% longer, while the line contact stylus may be useful 100% longer than the elliptical. Other styli like shibata and hyper-elliptical etc. will be between elliptical and line contact styli, while the best 6 designs (Stereohedron, Microridge, MicroTracer, Replicant, VdH1, and Gyger 1) will go the longest without obviously making a track due to contact in the groove. I'm trusting that there are no huge improvements in vinyl in 1992 since CBS Labs went thru this testing regimen.