So far people seem to discuss mostly straight cut and cat cuts for hammocks. When analyzing the cat cut gathered ends hammocks, obviously we need to distinguish the effects of the "short edge cat cuts" versus those of the "long edge cat cuts".
Based on the geometry, I would think that the long edges cat cut reduce the walled in effect (floppy sides), while the short edge cat cut reduce the calf ridge pressure.
When sitting with feet hanging down:
I think that the "short edges cat cut", not the "long edges cat cut", give the improved back support (firm back to lean back on). As far as the decreased leg comfort (bucket seat) I think both play a role: basically the short egde cat cut pulls the edge taut, but the long edge cat cut reduces this by removing some of the offending material.
But what if someone wants to improve overall comfort when sitting, and in particular low back support?
Perhaps one could do a special cut on one-half of the short edges and a straight cut on the other half of the short edges. The side of the hammock with the special cuts would offer more support for the back and head, while the straight cut of the other half would avoid the bucket seat problem.
For example if the special cuts were concave near the center (as in Option B in the attached drawing), instead of convex as the cat cuts are, it could give more low back support and a more natural spine positioning.
Would it make the hammock weaker (by using a concave cut, near the convexity point there might be increased tension)?