I'm confused about how Studio Surface > Rebuild works, and generally depends on trial-and-error in using it. I believe that better understanding would definitely lead to more efficient use of the core surfacing tool. Let me present an example.
I choose to start from two sections (one degree-3, one degree-2) and two guides (both degree-5). All of them are of single segment.
In Case.1, I don't rebuild sections or guides, but SS automatically rebuilds the sections by adding a knot, possibly to achieve specified G0/G1 tolerance, and (in my understanding) to do its best to achieve G2 (target tolerance unknown).
In Case.2, I rebuild the sections only (Degree and Tolerance, degree=3). To ask SS to forget G2, I set G2 tolerance = 10. As expected, SS doesn't care about G2.
Q: With loose tolerance, why does Case.2 still add so many knots to the sections?
Case.1 
Case.2
As in some of my other questions, here I'm not trying to fix the model, but hope to understand how the command works. Thank you!