I'm now working on my fourth quilt like the one in my guide, and in my experience, 2 yards is as little apex as I could order and still finish the quilt. I actually do use some of the leftover Apex to finish the length. The quilt I make for myself at 5'10" is about 75" long, so the 72" shipped is still too short. So I sew two pieces of insulation together (one piece from the leftovers) to get the full length.
But going with 1 yard instead would leave me very short because of the width of the quilt I designed. I really like the 50" width, which takes up 5/6 of the insulation and leaves me with a piece of insulation that is about 10"x72" (with a bit more along the taper of the foot). This isn't a whole lot of waste considering I usually use another piece of Apex that is about 4"x50" to finish the length. I think 1 yard would just leave you far too short regardless of how you used the insulation.
If you want a use for the rest of the insulation, you may be able to get away with one of these guys that another BPL member posted. It seems nice, and I plan to try it myself soon: