The sizes she has given for that one block are probably due to the fact that one can't buy the fabric by the yard (not talking about specialty cuts -- fat quarters, layer cakes, jelly rolls, etc.) cut smaller than 1/8 yard in most places. The designer assumes one will be making more than one block, likely with different colors but same background in most blocks. A 60" x 60" quilt probably won't use more than 2.5 yards all together on the front.
Jan in VA