When I was young, I squeaked by in Final Fantasy Tactics the first time without really understanding how to play other than brute forcing and over leveling, even though I was still being as strategic as I could. I'd only played Shining Force 2 before that and never got that far in it.
Replaying it when I got a little older made a world of difference, especially when you start trying to pursue stealing or item discovering one-chance items.
Shit, I'd say I didn't even understand Final Fantasy IV when I first played it on SNES either. I was always running from random battles to avoid the tedium, having to abuse potions and milking my money dry buying them (which also made me avoid battles, to avoid needing to recover), and never having enough money to outfit myself properly. I did go all the way, though, somehow. I understood all these great jrpgs by the end of the SNES gen, ofc, but it was a rough start.
Probably Dark Souls? I've sped through it in 35 hours and got the platinum at 60 but I tanked my way through most of the game. Most people would say I didn't do something right, but that's souls fans for you. Platinuming the game and go through it 5 times isn't really learning how to play it.
No matter how you play, there's a fellow Souls fan to tell you that you did it wrong. I tanked the hell out of both Demon's and Dark Souls, with protection spells like iron skin on an agility build. I play them much differently now ofc, but then again I play them a lot of different ways when the mood strikes. Still, watching Kay play Demon's Souls blind put a ton of stuff in perspective about how much I failed my way through it. Didn't stop me from loving every minute of it.