I switched some disc concepts around last year and honestly haven't fallen off of it. Let me explain.
I am a firm believer that we throw discs far faster than we should be throwing. Mainly we do it because we crutch on them a bit and it makes us feel more confident. Watching guys throw 11-13 speeds 300 feet is... Sad. "I need the disc speed to get there." ... No, the discs "speed" has nothing to do with it. I've watched you throw slower discs 100 feet further on a regular basis. (This is a real conversation I have with a friend who loves his cranks, but he throws some of his slower discs as far or further with ease)
I've always been a proponent of trying to throw in your speed range. But I, as everyone does, over rated my abilities for a long time. So I would try and throw 11's and 13's to much when I wanted that big distance but got nothing. Why? Because you start trying way to hard and all sorts of other things go on that you hurt your game more than anything.
So I changed the core of my bag to 6 speeds. Why? Because lets look at this from a different point of view. Lets look at it from a "what is this disc capable of" standpoint, vs a what am I capable of standpoint. 6/7 speeds are good for 400 feet of distance with good form. And pretty easy 350-400 of distance with good form. Not grip and rip, but just clean good form they can get you some good sneaky distance. And insane amounts of control as well.
I'd put 9/10 speeds in the 450 range. I consider 9/10 a control driver speed. These discs are more than capable of reaching out this far and designed to do it. These big 11/12/13 speed discs are designed for people throwing 450+
Guys gripping on 13/14 speeds who can throw 300 feet. ... When the disc is designed for 500+
Can you anyways? sure. But you're actually hurting yourself trying to throw a disc that needs higher speeds in flight to fly well trying to crank on it.
So lets back it off, throw discs that require a speed closer to what the average disc golfer throws, around 50-60mph. Suddenly disc golf becomes a bit different as we can casually throw 300-350 with a 6/7 speed and hit tight lines and gaps, shape shots. We can focus really really hard on that clean easy form that lets us play longer and less tired.
We can have fun watching out friends huck 13 speeds 300 feet while we casually fly 6/7 speeds 300 feet.
So what am I trying to say?
You probably should be throwing fairways and fast fairways more. There is a reason pro's are throwing them. They are super easy to control and respond well to lots of power levels. And you dont have to try and strugglebus your distance force flexing your destroyers terribly cause you think you have the skill level to throw the destroyer.
I've enjoyed golfing so much having a huge core bag of 6 speeds. I got a few mids, and I've got a few faster discs in there too. But I reach for the core 6 speeds first, until I need discs to do very specific things. Then I move up into my 9's. And I have 3 11's as well, but I'm throwing 150 class 11 speed defy's which.. are easy throwers. ... But annoyingly, I can't really throw those defy's further than my craves. And I throw my gazelle further than all of those (6 speed). The defy's are there mainly for shot shapes. Not many 6 speeds wanna give me that shot shape.
So, if your excuse as to why you throw all the 12 speeds is shot shapes. I have some ocean front property to sell you here in tennessee.
Because the realistic answer as to why people dont throw slower discs is that it's an mental thing. You "think" you need those high speed discs, when the reality is, you could be playing far better golf than you are if you took a piece of humble pie.
That. and its far more rewarding to outdrive people slinging 12 speeds when you just casually tossing mids.