My experience seems to be the opposite of most on this topic. I've got 2500-3000 wheel-on (Wahoo Kickr Snap) trainer miles on a previously used 28mm Continental GP 5000 since last fall and it still looks perfectly fine, showing zero signs of accelerated wear. If anything, it's showing significantly less wear than I would expect to see. I've also never seen bits of rubber on the floor near the roller, which I often see others mention. I run my tire at 80psi and about 2.5 turns on the dial (after the roller makes contact with the tire), which seems to be just enough pressure to prevent slipping. I also always release the roller when I'm done riding.
When I first got my Kickr Snap in Sept-Oct 2020, I had intended to buy a dedicated trainer tire for it, but never got around to it. I just rode this 28mm GP 5000 all winter on it and it was fine. I have another bike I primarily ride outside, so this tire only saw a few outdoor rides over the summer, less than 200 miles, but it's back indoors on the trainer again and so far looks the same. At some point I'll swap the front and rear, but now the idea of buying a dedicated trainer tire to save wear seems crazy to me.
I took this photo of the tire back in September when having this discussion in another thread. It's probably around 2000 trainer miles in at this point, plus maybe 1000 outdoor miles prior to that. Since this photo I've added another 300-400 trainer miles. It looks the same and I'll be surprised if I don't get at least another 1000 out of it:
