Having read criminal law textbooks many a late night at the coffee lounges and libraries, I can quickly and easily think of "normal defensive situations" that easily require more than five rounds. Epic circumstances are the type of circumstances whenever the situation becomes defensive enough to justify deadly force. IN other words, don't just think that you're fine with five rounds, or ten rounds, or forty rounds, because you may be, or you may not be.
Reading all the cases and the crazy scenarios and whatnot, I have a lot of loaded guns and a lot of loaded mags and bags of ammo near and apart from different guns. Why? Well, I can answer "why not" - cause it might happen to be that time when you need 40 rounds and new york reloads! (you know, like Doom, but real world. Hmmm, I should get some brass knuckles for when the chainsaw ammo runs dry)...
Of course, I wouldn't give advice. Your crystal ball may vary.