I'm no expert. I do what seems logical I know it's hard to start as a beginner (and I did it 20 years ago so i'm sure its worse now) and having to figure out what discs are what and will do what without anyone to help out and teach you. I started out just trying stuff- my first disc was a Millenium LF when it was considered a "big" disc. Anyone remember those days?
I didn't know any better so to minimize disc flipping I adopted a minimalist approach for 19 years:
2 Distance Drivers - I started at LF, Beast, Wraith, Flash, Surge, Destroyer
1 Mid or Fairway - Gazelle became Buzzz, Teebird, Predator, then Firebird
1 Putter Mold - Rhyno became Challenger became Voodoo
This bag was built top down with an emphasis on drivers. When I dumped this bag last year, it was 20 discs, 4 molds: Voodoo, Firebird, Wraith, Destroyer. To make it work, I had to use every ounce of skill I had in a body that just wasn't skillful or athletic enough to pull it off.
After my 36th birthday and a massive dip in my distance and jump in my scores, I decided to rebuild. It's still a work in progress for sure, and I'm still finding my way, but I began to build a cart from the bottom up. The logic behind this is that most courses are built with holes averaging around 350'. Yes, pro courses exist where the average hole is 450-500' but most situations are not this way - and even on those courses, you rip a big drive... or two big drives - and put yourself in approach range of 350' and in. So I have adopted a Fairways and Greens mentality. Shaving strokes by playing smart, not far. Pick a logical point on the course that plays to my approach game and I put my disc there. To do this, I have to have consistency in my form... meaning more molds to do more things.
So, with that said, this is what I currently am working towards:
Inside 350' -
1 circle putter
1 approach / driving putter
1 Flip Mid
1 Flat Mid
1 Flex Mid
1 OS Mid
I know a lot of players would think "Woah, woah! Do you really need 6 Discs for inside 350'?" The answer, at least by my new logic is, absolutely. The goal with this approach is consistency. By having a mold for each shot, you can eliminate variables in the form of your shot (variables often lead to problems with form), thereby ensuring a consistent pull every time. I don't have to be the most skillful player on the course to throw a good round... I just have to know my skill, know my bag, and throw consistently every shot. So I practice by throwing every disc in my bag the same way. The only time I break from this form is to throw a utility shot- either a flex, flick flex, or a spike hyzer. Inside 250', I throw Plasma Envys. Outside 250', I have 4 mids to choose from to achieve the correct angle of approach - flat to right, flat to left, flex left to right, or flat straight
Outside 350'
1 S-US Driver (Flips)
1 S-OS Driver (Control - Primary)
1 OS Driver (Wind)
1 S-OS Lightweight Driver (Big Distance)
For the driver classes, I've backed off on speed in favor of control - I'm carrying MVP's 18.5mm class and while I sacrifice some distance here, I have more control to reach a safe point I want to be at on the fairway. Keeping discs in the fairways and setting myself up for good approaches is better than throwing an extra 35'-50' and burying myself with a bad lie either OB or behind some obstacle I don't want to be behind. My home course, Carrollton Park in St. Louis has a lot of "obstacles" due to it being a former neighborhood. Playing it everyday has really forced me to focus on the fairway and on how to stay inbounds along narrow sections and avoid the sure stroke adder that is a former row of trees or bamboo or garden ties between what use to be neighboring houses.
Anyways - that's my logic, take it or leave it.