sometimes i will go for days without switching, then i will go through a phase where i change every day. it really depends. since i got my rebecca minkoff MA (got it in july), i have been using that pretty much everday unless the weather is bad (i have not treated this bag), or if I am going somewhere I don't want to take it (for example, i do not take this bag to the movies because I am too anal of spilling popcorn grease on it...).