It largely depends on the game and how difficult it is to achieve 100%, not that I don't make an effort regardless, assuming I'm enjoying playing through said game.
For visual novels, I'll try to unlock all of the endings, even the BAD END ones. I'm one route away from 100% (and currently working on it) for the ONE: Kagayaku Kisetsu e dating sim.
For Pokemon, I think I've only done 100% in Leaf Green. I made an attempt in Platinum and Y, achieving everything except the toughest battle facility-related ones because of stupid RNG in said battle facilities. Which is why I don't want to delete the save files in those games, I have full Pokedexes and stuff that I don't want to lose.
This year alone, I've also done 100% of Another Code: Recollection and Princess Peach Showtime.
I've given up on getting all the Nook Mile achievements in ACNH however; the ones I have left are mind-numbingly repetitive. I'm not going to catch 5,000 random fish, for instance.
And that's not counting the multitude of JRPG's I've played over the years. Some I've completed 100% (several of the Atelier games, the 3DS remake of Radiant Historia, Golden Sun Dark Dawn, some of the Fire Emblem games), some others, I'm close except for a few of the most difficult/time consuming achievements (Tales of the Abyss, a couple OTHER of the Atelier and Fire Emblem games, and I guess you could technically file Pokemon Platinum and Y in this category too.)
These are mostly games that I've enjoyed. If I don't like a game, there's no way in hell I'm gonna even try, lol