Thank you all for sharing your thoughts and resources! It seems all sources agree that the
spacing between letters should be at least one unit (the width inside a letter u), even without specifically "measuring".
My question was not a general question about spacing, I was specifically curious why the letters w, v, b, and o are shown with a final stroke of 1/2 space, either explained in words or on a grid in the examples I've attached.
The reason I'm asking is because when I practice individual letters as they are taught historically,
my habit is to make the final stroke 1/2 space. So when I'm writing a word, I automatically finish the letter this way and
as a result, the spacing is too tight. I understand that you should be thinking ahead about the following letter, but if I was teaching this to someone else, I would have them practice these letters with an exiting stroke of 1 space so the habit is already there