Gauge As You Go

This is a good tip that I found in my Stitch 'N Bitch Page-A-Day calendar:

"Ever finish your sweater and find that it doesn't fit in spite of careful gauging? That's probably because you didn't check your gauge while you were knitting as well. After you have knit about 12 inches, get out the ruler and see how you're doing. Hold your knitting up vertically because the stitches hang the way they will eventually be worn. If the gauge isn't working at 12 inches, you won't have that much to frog"

I never thought of checking gauge this way but it makes sense!