Rhino has about a thousand unnecessary clicks and steps that really tears on my RSI, but one that doesn’t just do that, but also either fails or creates infuriating mistakes you don’t immediately notice, is the implicit trim direction that Rhino creates internally without ever showing or telling you.
Yes, people have explained the hidden rules that govern this to me many times. It doesn’t matter, because I shouldn’t have to spin the model around in order to see if an edge or curve might be planar in some angle.
99% of the time, I want to Trim Direction=Normal (or Pull as Rhino calls it).
I’ve only used Rhino for a year, but I think I’ve already wasted several hours on figuring out why my Trims so often fail, and these days, I often go through the extra steps of DupEdge/Intersect, Fin and 3xExtendSrf which is a chore.
(Now, an ExtendCuttingSurface option in addition to the current line option (which never works) would also be nice, but I’ll keep this topic to the above single request.)