When I do a checkerboard pattern, I tape the covering to a piece of card stock and use a paper cutter. I remove the backing, tape the covering to the card stock and cut strips. Once the strips are all cut to the correct width, I then use a tape measure and mark the length of the squares the same size as the width. I then stack 3 strips, and cut with the paper cutter. Each wack of the cutter produces three perfect squares...

Here is a pic of my SlowPoke that I did using 21st Century fabric.
The checkerboard is not as large of an area as the others have done, but the corners all touch and the pattern lines up on the other side.