I’m confused when you say your HSTs don’t have points outside of the 1/4” seam line. Are you talking about this before or after you stitch your HST to another unit? Can you post a picture of the HST that you get when you use this method?
If yours look like the ones in figure 6 on this link then they are correct.
https://www.coralandco.com/blog/half...t-a-time-chart