The kid is not very good at tidying up after herself. It doesn't matter if she has storage spots - even if they are labelled.
The best example of her pigginess occurred after we spent the afternoon tidying up - finding placed for the new Christmas toys, etc... I was running her bath and discovered a pair of socks stuffed behind her stool. "Seriously, kid! Why are you leaving socks in the bathroom? Put them away." Twenty minutes later, she is still in the bathtub (she is 6 so I don't think she needs me in there the whole time) and what do I discover thrown on the floor - far, far away from her laundry hamper? The socks. Her excuse? "I was going really fast and got distracted." I call piggy poop on that excuse!
Sadly, the messy gene is genetic. My boss can confirm that from the state of my desk. Although I swear there is a method to my madness (and I don't have a bookcase - instead I have a photocopier sized printer). I don't just randomly through socks across my desk and hope they land where they are supposed to.