I have at least four different styles of handwriting. One for hurried-note taking, one for carefully penned birthday or other special messages, one for addressing envelopes or leaving important messages USUALLY ALL IN CAPS and another more flowing prettier, more curly style for when I'm in a flourishy mood.
Rather than seeing this change of styles as symptomatic of any schizophrenic tendencies, it's been an advantage - my handwriting has been blown up to billboard size and used on banners, adorned shopping malls, and used in brochures and ads. Being such a type fan, I found this article on handwriting and typography by themaninblue really interesting. He asked a number of prominent typographers to send him a scan of their handwriting. Interestingly enough, some designers have handwriting not unlike doctors!