Rehearsing the worst case scenarios or negative visualization is a very powerful tool, which paradoxically allows you to become more relaxed and therefore, more response-able, i.e., able to chose your response if you get thrown a curveball question or if you flub and make a mistake in the middle of a live broadcast.
With routines, you don’t want your threshold for “success” to be checking 100% of the boxes. Look for 3/5 wins or 2/5 wins. Otherwise, the human inclination is self-sabotage with “Well, I miss A or B, so I failed today,” or “Now today is going to be harder” and it becomes a self-fulfilling prophecy.
The physiological or psychological effects are so fascinating, like you said, because you’ll do it for a couple of days and you’re like, whatever. Then you hit this sort of inflection point where you just drop from 200 RPMs to 150. You’re like, “Whoa. Okay. This is different”. The whole week, you’re kind of zenned out.