Mxsmanic wrote:
At what point does uneven terrain become "mountain flying"? Do
rolling hills represent a problem? Is there a threshold of ruggedness
or altitude or some other distinctive characteristic of terrain (other
than variable elevation) that serves as a warning that mountain flying
skills will be necessary?

If you don't have mountain flying skills, and your departure and
destination are on opposite sides of a mountain range that is too long
to practically go around, what's the plan?

In California we define Mountain Flying as anything East. Usually
anything with terrain over about 7,000 feet is Mountain Flying.

-Robert