IMO okay advice for specific types of issues, but way too prescriptive to work well generally.

Steps 3-4-5 are good, and breaking it down like that could be helpful to readers, but in my mind, it should be so well practiced and executed so naturally that it feels like a single step. I also think there ought to have been a mention of the fast iterative experimentation where 3-4-5 is repeated.

Break the build (and block other devs)? Is this a 1-team company?

Write a test first? Maybe, if you've already got a well isolated, somewhat understood problem whose solution won't require deeper restructuring.

Immediately "Brainstorm as many hypotheses ... as you can think of"? Inefficient if you already have a good idea of what's wrong (wasting time guessing), and also inefficient if you have absolutely no idea what's wrong (wasting time with uneducated guesses).