This question seems to come up regularly. Yes, you can get a good shave, even BBS with one pass, at least what I define as one pass. I do this every time I shave. It is not, however, entirely WTG, and it does not mean that any part of my face only sees one stroke of the razor.

I use what I call a single natural pass. This means that I apply lather and go over my face with a series of natural strokes. Sometimes these strokes are WTG, sometimes ATG, and sometimes XTG. It all depends on which way the hair grows and what stroke is natural for that part of my face. I also overlap the coverage areas of each stroke, so each part of my face usually sees the blade at least twice, and often three times.

I never relather and go over any part of my face in a radically different direction (this is what I would call a second pass).

If, after rinsing with cool water, I notice a spot I may have missed, I will do a water only touch up with the same natural pass to clean up this area. In my opinion, these missed spots indicate a problem with technique, not a systemic need to do multiple passes. I don't always miss places, and the locations of these misses are random.

As far as I can tell by palpation, there is no difference in the quality of the shave on areas where the natural stroke is WTG, ATG or XTG, if it was a proper stroke (or series of strokes in reality), then the shave is smooth. If it is not smooth, then I did something wrong.