Face Mapping & Shaving Angles
I find that the razor tells me which direction the hairs grow MUCH more reliably than feeling with my hand, or looking a 3 day stubble in the mirror. The direction also seems to change a little based on which direction I stretch the skin from, and how hard I stretch the skin.
ie: On the 2nd pass, and using a 20-30 degree angle:
WTG feels like it's not cutting anything (unless you use pressure -don't).
ATG feels very irritating to the skin, and often gets "stuck" (since you are using a WTG angle).
XTG feels like it's cutting about 1/2 as much as the 1st pass going WTG and is about the same amount of irritating to the skin as the 1st WTG pass.
ps: I find that using No inward pressure at all on any pass, plus using a lower angle on XTG, and an very low angle on ATG eliminates skin irritation that lasts longer than shaving 1/4 of my face. ie: For XTG, I make the spine about twice as close to my face as it was for WTG, and for ATG, I make it twice as close as it was for WTG.