Too many is when they're bursting the seams of my house I'm not sure if I'll get to the point where I think I have too many, but since we're moving soon, I may think too many is when it takes me an entire van trip or two to move them all.
I used to think 3 or 4 was all I needed. Since finding EF though my collection has greatly increased (got one order today and another one shipped today). There are so many variations out there that each one can be used to do something different. I was talking with a friend of mine and we this topic came up, we came to the conclusion that if you had 365 you would have a different one for every day