I experienced the same thing. Calc I was the most difficult and I may have even had to retake it. Calc II and III were fine, Diff-q was fine, Discrete Structures I fucked up hard on.
We have multiple sealed booster boxes of each of the wotc eras, skyridge aquapolis base set 1st print, 2nd editions, gym heroes and challengers the neo series the island cards, delta species etc full sets of the gold stars and shining cards, both stopped closer to the 2020s but every now and then still pick up things I know we have master sets in there from the older ones all mint since they went straight into the collection, a lot of coro coro mews and even more freaking charizards! Crazy enough my favorite sets aren't even the more expensive ones but they're the gym ones (gym heroes and challengers) also the first dark ones (dark dragonite being one of my favorite there and dark dugtrio) almost nothings in psa but everything is definitely mint! The shining we have multiple of since we had a ton of boxes we ripped growing up when we both started working with our dad; yes right now the wave on pokemon is insane, i went to see if I could grab a 30th since it has multiple art works but u saw the line and said fuck that nonsense i don't want it that bad lol I'm grabbing a few the the becket 10s rn of N's pokemon because their art looks insane to me, the zekrom and reshiram to put on display in one of my rooms with collectibles, i do think it'll slow down but I recall last year buying a card for 2 bucks online (liked the artwork) now its worth 25 bucks ungraded, so again i know the growth is limited especially with reprints but I still think there's a ton to be gained to those that hold (rn after the hype of 30th i see some cards going down)
The chase mew in that series I'm not a fan of so im skipping it completely but some of those cards ill definitely like to have (i do hear their hit rate is very favorable so I don't expect them to be worth much as the weeks go by)