Mid-size phones such as Apple's iPhone see the most regular usage, while 'phablets' are a 'fad,' with the least amount of regular usage among mobile devices, a new report has found.Related StoriesMP3 resale ban could close doors for Apple and Amazon's second-hand media plansApple: USPTO reexamination of patent in Samsung suit isn't completeiPhone 6 rumours: New iPhone production to begin this quarter ahead