
I dug through some of my books and found this graphic in "Sign Painting, the New Way" by Steve Prohaska. Signs of the Times, 1964.
Most of the lettering practice pages I found were for show card writers and were usually showing how to do a single stroke, with a clean up stroke at the top and bottom. It would be faster if someone could master the brush well enough, and it works best when the letters are relatively small.
In the example above, it takes two strokes for the verticals and some of the horizontals. This technique works for larger letters, or where the practical limits of the width of the brush are exceeded.
I watched Glen Newcomer letter that way for hours and hours and it influenced how I did it from that point forward. In reality, I think most people eventually adopt a hybrid approach. Use one stroke when it feels right or when the stroke was thin enough for the brush. For example, the horizontal bar on an A might not need two strokes.

I just added the red on the image here. The tip of the brush is set down in the corner of the stroke, then pressure is applied as the brush is slid slightly across and down, then dragged down. Near the end of the stroke, the brush is twisted slightly as it is raised to finish off the stroke. Maybe someone else can describe the action better than I just did, but if you tried to replicate the shapes in red with one stroke, you could figure it out. It would be the same concept for the other side of the letter. Top and bottom strokes would also be similar.
Maybe the examples above will help anyone trying to learn the strokes.
Cheers,
Mike Jackson