It was when I first started using the 12x18, I usually ended up playing at 800x600 windowed which reduced the area to something like 7x5in. But now it really doesn't matter I can play at any size and adjust to it within the first few notes. Each to their own I rather use my whole arm and wrist than just my wrist. I tried it both ways and it really makes no difference to me and since I have the tablet area I might as well use it. When you scale up the area so does the game like a slider my slider space is about the size 50 cent piece which from the GUI setting pics thats about what everyones active area is set to so Its kinda hard to fuck that up XD
Mainly I own this tablet for the sole purpose of utilizing my whole arm to do work than my wrist just like you do on a canvas, Not only that the grip pen exploits this by being thick like a brush. Its a sad shame since wacom discontinued the 12x18 tablets with intuos 4's so I have nothing to look forward to when this old piece dies and its bad enough that OSU eats my pens up.