Quite often.
Especially after my annoying experience a few weeks ago. I was going to the Seabreak Path or whatever it is called to hatch an egg, and right before I went there, I forgot that stupid cave place is really foggy, so I just deposited my Staraptor with Defog.
I absolutely hate that fog. I always get haxx0rz3d by it. Even worse was, I entered a battle (accidentally). I had 3 eggs, 2 n00b-pokemon and my Palkia. My 2 n00boes were knocked out instantly, leaving me with my Lv.73/72 Palkia. Earth Power. No, fog haxxed. Surf. Knocked out the two opponents. 2 more pokemon, that completely owned Palkia due to MORE fog hax. I could maybe have won, but I didn't have the patience to try to. So I just turned the game off and then on again. When I realized I hadn't saved in like, one and a half hour, I didn't play Pokemon for days.