How many knives is too many? I'm of the opinion that "too many knives" is somewhere between no room for anything else and impossible to achieve.
Presently, I carry 3, at least for certain values of "knife".
I've got my EDC, a 4" blade Cold Steel Ti-Lite. Good knife, but it'll shred the insides of your pockets and your fingertips if you aren't careful. It's also stylish in the same way as a stiletto switchblade, which is good and bad. Real easy to use for fine precision stuff, even with a 4" blade, and it holds an edge fairly well (comes ridiculously sharp out of the box, too). This one hangs out in my right hip pocket, along with 2 mechanical pencils, a pen, and my alumawallet.
Next I've got a multitool, a Gerber Multi-Plier 600 or so. Thus far it works pretty well, and does the trick for needing a knife in polite company, because nobody bats an eye at a multi-tool. Or, almost nobody, I've managed to find whimpering ninnies who were surprised by my last, smallest knife I carry. Could stand to have a few more tools, since it comes with a MOLLE holster and doesn't have to fit in a pocket. Thanks to having a locking blade, I'd say it still technically counts as a knife. It rid.es on my left hip
The last one is a little credit card multitool. You can find these things for as low as $1 if you're willing to look around and wait a month while it makes its way over from China. It isn't ergonomic, but it works. The knife blade is VERY tiny, but in the right hands it can get stuff done. I've also had people who were put off by me carrying this thing and trying to use it as a knife. "Do you carry that with you all the time?" "Yes, and it isn't working very well for cutting this tubing. I also carry this (see item #1), I just try to use the other one in public because it's tiny and nonthreatening *easily snips tubing to length*" If you can find this at the cheap price, its probably worth buying a big stack of them to give to everyone you've ever met. It ain't great, but it works.
They aren't knives, but I also wear a pair of these in my shoes most of the time. With black laces, they're pretty much only visible if you look at the shoes in profile. Nice to have when I don't have a steel toe available.
Lately, I've been looking to upgrade and add to these. The Ti-Lite is nice, but I'm looking for a tougher lock up, and preferably something that won't punch holes in my pockets and such. The CS Spartan is presently the top contender, but I'm open to suggestions in the ~4" blade range for ~$50 (anything on the CS website can be found elsewhere for about half price). I want an off-hand knife for retention purposes, and have heard that this one is pretty good, and tiny enough that I can probably just tuck it behind the holster for my multitool without needing more belt space. I've got a Fury Tactical dive knife that I theoretically could use as an arm/leg knife, but I think I'd be better served by something else for most purposes. The grip on it is kind of terrible, but in a pinch it'd work, but I don't usually carry it. I'd like to add a neck and/or boot knife.
If someone ever actually has reason to check for all the knives I've got rattling around, it's probably going to raise some eyebrows. And be like the scene in so many cartoons and movies where there's the one weapon lover who's just taking guns and knives and stuff out of pockets for hours.