OK. So I am sure this has already been asked here but I can't find it, so I am going to ask it again! Can someone please, please, please explain the gauge thing? I understand it when you are using the yarn suggested in the pattern, but what if you are using a yarn different from the one suggested? How do you figure out if its on target? I have been knitting for while but have never been one to do swatches as it hasn't really been necessary. Now it is and I am confused!