So, I know the importance of points at extrema for rendering of PS outlines.
For TT outlines, I was surprised to see the construction shown below used for a circle, because the points controlling the extrema are off-curve, and there are no on-curve extrema in some glyphs. I am wondering which is true: (1) it doesn’t matter if the points at the extrema are off-curve points? After all, instructions can control their locations as well as on-curve points. Or (2) the preceding is technically true, but autohinters may expect on-curve points at the extrema, so it is a bad idea? Or (3) something else?
Of course, the fix would be simply to rotate the circle 45°. But there are a lot of these constructions, so it would not be trivial.