Sorry, but there's no context here. Half the time as compared to what? Or, who? If you are trying to say that you can learn a language faster than the traditional high school curriculum with greater comprehension and retention, I would say, "Of course you can!" In fact, I've gone through a course that teaches how to teach virtually any language using techniques proven by modern neuroscience. That's how I learned Spanish - since none of my high school Spanish stuck. I've actually written a number of Hubs on some of the lessons learned.
If you can provide a little more context, I would love to know what technique(s) you are referring to. I'm always looking for new ways to enhance the success of both me and my students.