I think that this is a great topic. I have only been playing for 2 years now but have progressed quickly. I have played both AM 1 and Open tournaments and done well in each. It has taken me a full 2 years of playing to get comfortable with my bag.
I have the core discs that arent going anywhere, Teebird, Buzzz, Destroyer, Ions but up until recently I have really been trying a lot of different molds and plastics out. I think the first thing that clicked for me was the plastic type that I stick to.
If I can get a disc in Champ/Z Glo I am going to throw it. I relized along time back that this was my favorite plastic, I like the consistancy the and the stablity the plastic brings to my game. I think that I will always be trading a few discs in and out of the bag other than my staples but the plastic is not going to change. I have slowed down on trying out new discs and am very happy with my bag the way it is right now, I dont see much coming or going. I do however find myself trying a new disc out for a certian type of shot I might want to make, like overhand or forehand roller. If I think that a certian disc might be a bit better at accomplishing that task then I will generaly give it a try during field practice.