I've been playing Super Metroid through rentals, borrowing, and finally owning on the Wii (Hey, I wanted a copy for SNES but never could find one around here) for over a decade and a half; I've finished it at least 10 times, almost every time deciding to play it lengthily and savor it, going for 100% completion rather than record fast times, rediscovering every inch of the game.
However, every single time I play back through, with no exceptions, I find out something new I didn't know. Back then it would be more obvious things like the Wall Jump, but with subsequent playthroughs (and occasionally with peeks at guides or talking with people) it's been things such as the Crystal Flash, the Charge Beam + any single other beam + super bomb special moves, the fact you can 'rescue' the good native animals of Zebes as you're escaping from the self-destruct system, etc.
Does this ever happen with you? Do you still learn new things in subsequent playthroughs through the game? Maybe you'd like to share some even crazier things that a lot of people might not know about, be they actual purposely-programmed secret actions or glitches.
Nope, on the second play through I knew every little quirk and technique. I just wish I could remember where the rooms and secret passages were though to shorten the timings > >
I think the last thing I learned was that you could still do a spinning wall jump while charging you beam if you release the beam button during the first jump.
Or something like that.