To understand how Studio Surface works seems not to be an easy job.
I thought that (1) perfectly matched input curves and (2) four or less input curves would definitely yield a surface of (A) high quality and (B) low continuity deviation. Especially "four or less input curves" should lead to a "relaxed" surface.
It seems that I was wrong. Hope to have your comments. Thanks!
4 perfectly matched input curves
(TOP) loose tolerance > high deviation ; (BOTTOM) tight tolerance > heavy pole structures