This is “Peacock Tapestry” by retired needlework designer Teresa Wentzler. I received the kit as a birthday gift in 1997, and finished the stitching in 2008. So yes, your math is correct: this piece took eleven years to stitch!
At approximately 14×22″, you can see why! The piece is primarily cross stitch (cotton floss on cotton fabric), with some specialty stitches (like the eyelets in the border) and beadwork. Much of the piece uses blended floss (two different colors of thread in the needle at the same time), which is one factor that accounts for the depth and richness of the design. (Another factor would be the dog hair it picked up during the last 5 years of its life!)
Click the thumbnails for larger versions of the images.