If you're IFR, solo and you go for the IAP in VMC then that's no problem. However, in this scenario no view limiting devices can be used and you would conduct the approach as if you would in IMC - occasionally checking to see whether you'd gone visual. Nothing wrong with taking the approach down to DA/MDA but you have a responsibility to other airspace users to keep the scan going outside as well as in - which would detract from the normal training process of "head in" until the relevant point of the approach.