Fond memories with FF7: I had just beaten the game and was sitting there thinking "So, now what? Should I make a stab at the Weapons? Sure, why not. I´ll just go to North Crater, pick a nice spot and gain some AP. Gotta have me some strong materia." After hours of fighting the same enemies over and over, I start wondering, how long does it take for these buggers to grow. Finally I notice a tiny detail concerning my weapons of choice: No materia growth.
To this day I haven´t beaten any of the weapons, and never will, cause they suck.
(I probably have done lots of stupid things in games, but this instance came to mind first.)