I don't understand your point. In no case can a sorcerer trade out spells while in the middle of some large dungeon, so exactly what does that mean to my comments? Since we're talking about 17+ level planning, I would hope your point somehow relates to that. Are you suggesting, therefore, that you need to plan ahead for 17+ levels to beat some large dungeon way in the future and that without such planning it wouldn't be possible? I just plain don't have a clue where you were going with this line of reasoning.