Just a curiosity here... I'm a bit of a mixed bag on this. I have some old notebooks filled with outlines and random ideas, plus some files on my computer (that I've transferred from thumb drive to thumb drive and computer to computer over the years) with things I never finished or submitted anywhere. I cringe when I read most of it. HOLY CRAP is it evident that I've improved in every single aspect of creating from when I first jotted down some of this drivel. I guess that's a good thing to realize, but some of the stuff I revisit I ask myself just what on earth was I thinking then? So, what, if anything, do you do with old ideas or projects that you've shelved? Do you leave them for a rainy day to revisit, or just let them rot? Do you keep them at all or discard/delete them? Do they actually reignite something that you can use currently?
I fire them up all the time. Invariably, I end up reshelving them for the same reasons. There's a burst of excitement and creavity at first, but then I'm like, wait a minute, this, this, and this still doesn't work. Every once and a while I see a way to fix it. But most times it's back to the kaput pile with little regret.
I have two shelves on my bookcase full of old stories I'll eventually look through and hate all over again. But! That doesn't mean I won't revisit them later and make them better. I never throw anything away or delete anything. Never know what might be golden garbage later in life.
My current project IS reworking an old story of mine that I first wrote ten years ago. True, I finished it back then, but it had some flaws to it that I'm fixing now. But it has turned into a very different story using the same characters and setting. And no, I don't get rid of my old stuff. As @Dogberry's Watch said, you never know if you can use it sometime.
I keep all the old and unfinished stuff. Some of it is serviceable, but most is all the cringe. In general though it is nice to look back and see how far/much I have improved as a writer.
Yeah, I've never deleted anything. I have original, DOS based Windows files that have been rolled through decades of upgrades, 5.25" floppies to 3.5" floppies to thumb drives to external hard drives to fucking cloud based thingies that I can access on my phone 25 years later. Nothing like reading something you wrote in 1995 while pumping gas in 2020 right? ETA: you know, I really like writing the word "floppies."
I revisited two old ideas last year and finally turned them into finished books. Both of them were at least a couple of years old and needed a complete rethink. There's nothing wrong with doing that if the ideas are still worthwhile.
Several years ago I pulled out the first novel I wrote and pretty much started giggling right from the start. It was so bad. I don't think I'll ever even try to rewrite that. My second novel was still a lot of cringe but a lot better.