thurs 20 may, page-184

The object was to give out the idea of 1 (very old) way to trade an index, and show you a trail distance using a rough measurement of the noise (the height of the box), so you can limit your risk.

If the height of the box was too big, wait for a smaller box.

If however you narrow your trail to limit your risk without using the price structure as a guide, you will get stopped out more frequently, and you will need to modify the strategy a fair bit.

Anyhow, a demo account and a few practice trades will either give you confidence, or show you the need to do some more work.