I had the same issue as Redback with the Cuben I used. It came in a roll width of about 137cm. I think Bluegum Mic is planning to use silnylon which has always come in wider rolls when I've bought it, usually 152cm or more.
I had originally intended to do a cost/weight comparison between making my pyramid with 4 panels (more expensive but lighter) versus 8 or more panels (heavier, cheaper). I would have liked to have had the option of spending more money to save some weight, but I quickly discovered that it was impossible to make 4 whole panels. The choice I was left with was between 10 panels and 12. At that point it didn't matter so much and I used 12.
I ended up using about 6 yards of fabric. Here's how I cut the panels from the 137cm (54 inch) roll:

Less panels in my case was mainly a weight issue because the 0.5 inch tape I used to join the Cuben is relatively heavy (approximately 1.8 g/m). The tape for the 10 panels weighed 1/3 as much as the Cuben panels themselves. At least 1/6 the weight of the finished tent (including guylines) was due to the tape and glue.
I think epoxy would have been lighter than tape but the tape was so quick and easy to work with. I really didn't miss sewing long seams one little bit.