I cant say I've never done it but I make a personal conscious decision whenever I watch someone playing to not do this. It is a real pet peave of mine.
"Oh I missed something back there? Well im sure its not directly pertaining to the main storyline, so if I miss an optional item that adds +stupid to my attack it doesnt bother me. Feel free to get it on your playthrough though." Im one of those gamers that reads walkthroughs when I get somewhere that the dungeon is non-linear. I dont like to miss something. But if I do I dont want to be called on it and heckled for it.

My brother does that alot. Fable 3 was a great example. There is a ton of optional crap to do in that game... Silver Keys etc... the typical Fable stuff. He always had more keys than I did at my point in the game. And he'd always make it a point to ask. "hey how many keys u got loalz?" Bah... If keys were needed to beat the game I'd care more.



/end rant

lol