You have to understand Zimmerman in context. If you look at knitting books of her time, you see that most of them emphasize blind following of pattern, to the point that you weren't even supposed to read ahead in the pattern beyond the line you were executing (!!!). So her books are basically about not being a knitting zombie.

I'm not very good at following rules exactly myself; that's why I'm a knitter and not a sewer. However, I think with a little experience you will find out exactly why gauge swatches are (usually) good time-saving devices, especially if you substitute yarns. I just had to redo about eight rows of knitting on a hat because the yarn and needle combination was not producing the fabric I wanted.