Well, they've been laid out for 20x30 sheets...but I don't know that I'd agree they've been optimized. Which is by no means a swipe at Sponz, his work is terrific and to be commended. But he's not designing the plans for automated cutting as much as he is for most users who will be hand cutting.
I didn't do it in most of my videos because I was trying to keep them short...but I regularly re-arrange the parts and manage to eliminate a sheet or more of foam.
I can pack pieces very closely together - closer than I'd want them if I was cutting by hand. I also eliminate pieces I don't need like motor pods (I either make them in batches or 3D print them now,) the poster board pieces, the 90 degree angles (since I have a nice plastic one) and on some designs optional parts or variations. The FT-29 I was able to eliminate a sheet but still keep all of the parts for example.
I've also noticed things like on the Simple Scout - in the build video I noticed that the laser kit has the pushrod guide holders inside one of the waste pieces in a fuselage part. In the plans they're separate. This isn't a great example because the SS can't be done in fewer than 3 sheets because each wing half NEEDS it's own sheet as does the main fuselage - and there aren't enough parts to fill all the rest of the space on 3 sheets so there's going to be wasted space and nesting those little bits doesn't really help on this particular plane. (It probably helps FT due to how they package for shipment - even if it means wasting more foam that likely saves more money over having to ship larger packages.)
So while Sponz does an outstanding job on the plans I would hesitate to call them optimized as I'm pretty sure that's not his intent. If they were optimized for our use they wouldn't be as friendly for people manually cutting and those are the primary target of the plans so those are who they should be optimized for. So - to be fully fair I could stay they're optimized...just not optimized for mechanized cutting
Of course they can be cut as-is just fine. And at $1 a sheet it feels silly to spend an extra 20 minutes to save one sheet of foam...but I enjoy the process and detest waste (which is why I have a big pile of foam scraps that are still big enough I could cut "something" out of them - I use them to cut repair parts out when needed.) So I take that little bit of time because I enjoy it - but I fully accept that it's not for everyone!