With the recent drama over HSTs and Gold Dots...
My carry P30, practice P30, and my P30SK are all vetted with the load and I have a practice load with a close POI and similar recoil. I have a practice gun and thus have no need to unload the gun in order to dry fire or practice at the range, so the carry gun stays loaded all the time. Per advice from Tom Givens and others, every six months or so I go to the range and do a series of cold drills with what was in the gun/on me and replace the ammo with fresh ammo. So, I figure that's a bare minimum of 36 rounds per six months -- 31 rounds in the gun and spare mag burned every six months and one round per month lost due to cleaning/lubing (I don't re-chamber them). All of that's probably more than a little paranoid but whatever. I had 500 rounds in an ammo can. I picked up another 200 I saw in a gun store the other day just because, so I've theoretically got enough ammo for the next two and a half years before I even break the seal on the ammo can.
Having nerded out about all of this, how much do you consider "enough" to have on hand for a CCW holder?