When I instructed at Jason Pridmore's Star Motorcycle School, I had plenty of opportunities to see many different types of riding styles. I have seen everything from riders hanging way off the side of the bike and trying to drag their knees riding at what seemed like 25km/h, to riders going quite quick and leaned over at MotoGP lean angles but sitting bolt upright. I always found it interesting to talk to individual students about their own particular style and body position, and - if they were having trouble - try and offer suggestions for improvement.
Usually, I only corrected the basics to help ensure the student would not come to grief: having the inside toes on the footpeg so they don't drag on the ground, keeping the upper body on or to the inside of the bike's centreline in a corner, bending the elbows to make steering easier, and so on. Beyond that, as long as they were comfortable with their riding position, I didn't try to force them into something new (and uncomfortable) that would distract them from working on something else.
When I started practicing yoga, I learned a lot about the human body and that a lot of that comfort on the motorcycle is determined simply by how your body is put together. It helps that my wife Deborah is a yoga instructor, and that she is quite knowledgeable when it comes to anatomy. Characteristics such as your height and weight are obviously important in a general sense, but there is much more to it than that.
For example, if you are tall but have disproportionately short arms by even a small amount, it may be difficult for you to keep your elbows bent while hanging off the bike in a turn. Another example: some people don't have enough flexibility to keep their upper body in-line with the bike when they move off the seat more than a couple of inches. How your joints are constructed can even make a difference; some people's hip sockets are oriented such that they simply can't stick a knee out very far, no matter how hard they try.
Your own body's characteristics will make certain positions or movements easier or more difficult, and this must be taken into account as part of your own riding style. The correct body position for you is one that makes you comfortable on the motorcycle - this is what will give you the most confidence in your riding.
That said, it's important that you note the difference between being comfortable and being lazy. It's not enough just to plunk your butt on the seat in a cozy position and leave it at that; experimentation is key, so that you can find how to use your body to its greatest effect, within that zone of comfort.