So what do most of you carry and what do you think "proper" ratios should look like?
Most of this is covered in my "How to Build a Bag" thread, but I'll chime in.
I really think it's more about the number of molds than it is the actual number of discs. The big difference between discs of the same mold of different beatnesses is fade. You can throw a more/less beat version of the same disc with more/less hyzer/anhyzer or OAT and get them to fly similarly, but the new ones will fade harder at the end of the flight.
Also, when people say discs "overlap" or are "redundant" they don't mean that they fly the same when thrown the same. They mean they can be used for the same shots. No a Coyote and Buzz don't fly exactly the same, but they're both neutral mids with minimal fade so they can perform most of the same shots as one another. You may have to throw them differently to perform those same shots, but they can do it none the less.
I think that for mids, unless you can do everything with one or two molds, you're way better off cutting down to one or two molds. I prefer one myself. If you can't do everything with those discs then there are probably some skills you're missing that could improve your game.
Putters are the same way but I feel stronger about only using one mold.
There are a couple different categories of drivers, so I think it takes more like 3-4 molds to cover everything unless you like maintaining a lot of different beatnesses of discs.
Here's what I have:
5 putters - 1 mold
2-3 mids - 1 mold
12 drivers - 5 molds
I am outside of what i need for drivers. I freely acknowledge this. I tend to carry a workable and a straight fairway driver, which is overlap, and I'm testing distance drivers to see which I like best. I don't want to go too in depth with it but it's really an even bigger mess than that. I have beat Spirits that overlap with my SOLF and Surge-SS and an X Avenger that I'm keeping just to see how it beats in. I don't have it listed up there because I don't actually throw it, but I carry a Star Destroyer just because of the name. Long story short, I have more room in my bag than I know what to do with so I fill it with "test" discs. I could probably knock it down to 2-3 molds without any problems. That's all I really use, anyway.
I guess the point of that last paragraph is that there might be reasons to carry discs outside of what's best for your development, but understanding what is best and why you're deviating can minimize the "damage."