I do think there is a thing called overkill.
Going to church on a sunday morning fully armed is one such example.
But walking into a dangerous neighborhood (gang territory, et al) because a friend/sig other is stranded and needs a ride outta there isn't over kill because often times they're probably more heavily armed than you are.
How much one should carry on their persons I think should be determined by where one is and the circumstances (as well as the time of day). A good MA-ist or warrior mind set should know and know how to judge appropriate weaponry to meet the situation however hypothetical it may be.
Oh sure there are those who think that "you never know when you'll end up in the middle of a gun battle inside of a McDonalds.
While it's possible... if the eatery is in a bad neighborhood... chances are not likely.
Being realistic, and being trained to deal with whatever situation that you find yourself in with whatever weaponry (or lack of) you have in your hands, should carry you through. All of that and a cool head.
I have my pocket folder and my SD training... roughly 90% of the time that would've been adequate. When I'm out camping or hiking in the deep woods I'll carry a large Dundee type knife on my person along with my folder, mainly because I don't worry so much about bears as I worry about hearing banjo music. Beyond that... meh.