Regarding the grind on a singing razor ( refered to as extra hollow grind I believe)... are they supposed to flex and follow the contours of the face thereby giving a closer shave? If they're designed for the tough beard, will a less than tough beard benifit from a singer?

... what is a vestigial secondary grind?

Are the extra hollow grinds more delicate ( fragile ) than full or half grounds? Are they more prone to damage and need honed more often?

Thanks, again
Zig