Style Changes?

[Sophieselt]

I was wondering as I browse- how often does Bal add or subtract a specific style each season? I have seen many older bags that don't seem to be around any longer- similar colors but different styles-
How often do they change them?

Thanks-

 

[Honeylicious]

I'm no expert but I think they introduce some new design every year or two??
like Velo was introduced in 2010 (correct me if I'm wrong)
this year we see new design like Polly and Kraft..