Carbon fibre filament doesn't make parts stronger the way most people imagine. The chopped fibres primarily add stiffness, dimensional stability, and creep resistance; tensile strength gains are modest. Knowing the difference is the whole game.
Where CF compounds earn their cost: parts that must not flex (brackets, mounts, jigs), parts that must hold dimension across temperature swings, and nylon's case specifically, taming PA's tendency to warp and creep. PA-CF is our structural workhorse for exactly those reasons.
Where they're wasted: parts that fail by impact (the fibres make some materials more brittle), and anything where ordinary PETG was already stiff enough. We spec CF when the job needs it, not because it sounds premium.