So, I used to play Gold/Silver religiously. I just loved the game to pieces - still do. I would play through again and again, probably not doing too much different, but just enjoying the journey so much. Save files probably wouldn't go much further beyond 60 hours, because once I beat Red, it'd feel like there wasn't much left for doing (I just wasn't interested in filling the Pokédex, since I'd never have anyone to trade with, and so it'd never be fully complete).
This trend persisted, to lessening extents, with each generation up to around Black 2/White 2, which came out when I was in my second year of college or so. From DPPt onwards I started investing in teams beyond just soloing with my starter, and that alone meant more time was spent on a save file.
Life was also starting to get a lot busier, and the games were also a lot chunkier - way more Pokémon, way more things to do in the postgame like Battle Frontiers and Pokemon World Tournaments. So while I had less time to play, I was investing more into my save files whenever I did.
I still have my original save files from White 2, Y, ORAS, Sun/Ultra Sun, and Shield. I just bought the second pair to each of them if I felt like replaying the story (yay for being a working adult... money for games, no time to play em!).
Nowadays rather than my save files starting over, they just accumulate. Usually they reach the 400~ hour mark or so before I move on to the next generation of games "for good", and while most of the Pokémon are migrated to Home, I like to keep the file's progress for nostalgia's sake. Always nicer to revisit a completed save file than a blank save.