As long as you know what each disc does, and you are shooting well, its never too many.
I, however, am a minimalist and limiting the number of molds is more important than the number of actual discs.
FOr example...my bag is
2 champ orcs (164-beat, 164-newish) for controllable distance on a straight or hyzer line
2 pro orcs (175-beat, 175-beat) for big s-curves and hyzer flips
2 pro orcs (163-beat, 163-super beat) for turnovers, big hyzer flip shots, and distance rollers
1 z pred (174-new) and 1 z flick (155-new) for overstable and forehand duties
2 champ leopards (170-newish, 156-new) for controllable fairway and woods shots. THe heavier is obviously for more fade and the lighter for turnovers
2 star leopards (176-new, 172-beat) for straight, controlled shots...new one is being beaten in as a backup for the 172
2 dx leopards (150-thrashed, 168-beat) for rollers, high flex shots, and hyzerflip-to sharp right turn
4 dx rocs (180-new, 179-beat, 179-more beat, 167-superbeat) for all midrange needs from hyzer to straight hyzer to straight to turnover
1 kc roc (180-new) for all overstable midrange needs
1 s wizard (172-semi beat) for straight to turnover upshots
2 m wizards (174-newish, 174-slightly beat) for all putting, jump putting, hyzer approaches, flex approaches, and high power straight approaches
so in all, that is 20 discs, but only 6 molds. Often, Ill even throw in a brand new 175 champ orc as my overstable disc, and that cuts it to 20 discs and only 4 molds. This reduced mold count gives me a consistent feel when I am throwing, so I dont need to adjust my grip for a new disc, just pick the right disc for the shot.
Just my philosophy when it comes to disc golf. courtesy of Blake T at DGR