When I first create a sphere, it has a nice UV map, like this:
However, when I try UV unwrapping with identical seams, I get this:
Using cylinder or sphere projection does better, but it's still wonky at the edges:
I am currently trying to UV unwrap a bottle, and I'd like the "fresh mesh" UV style, where the map spreads out over the image rather than trying to make individual faces less contorted, thus making the texture easier to paint as a whole in an external image program.
One thing I've tried is arranging the UV vertices of the bottle edge (before a Screw modifier) to be in a straight line, then letting the Screw modifier turn it into a Grid. This sort-of works, but the straight-line arrangement doesn't work well for portions of the bottle that are horizontal, and leaves them with zero texture height. If I had a way to evenly distribute the rings of the bottle from top to bottom on the texture, that would do.
Oddly enough, the curve this bottle came from seemed to have this UV automatically, but I could not preserve it when converting to mesh.