how do you know if you are using the wrong axis? for example if my eye has an axis 180 but I use an axis 170 lens. do the directional blur move in the other direction?
Stenopaeic slit is the easiest way to find your axis, a trial frame will have the angles marked. The JCC lens is used more in the US, but it is more fiddly on both the patient and practitioner end, depends on judging between two blurry images.
The directional blur would change slightly with a 10 degree change. 90 degrees reverses the power needed.
Several people seem to have wandering axis of astigmatism. Even multiple readings in the same day it seems to drift. Might take a large number of readings before making changes.