IMO, anything more than 5 good pairs of shoes for work, crosses over into the excessive classification. You won't have time to properly maintain and shine them otherwise. Trading up is fine.
As for casual and sport, anything more than 10 crosses over into the excessive classification. 2 pairs of trainers and 8 casual shoes is plenty.
That's a total of 15 pairs of shoes sitting in a closet!
Having said that, all the people that actually add value to this thread, add value because they are excessive in what they do (not me). It's highly admirable.
P.S Grats on the new news shoes! :D.