I was thinking the exact same thing 2 days ago and wondering how likely is it for me to do these 4 things 100% during a match at least for once in my lifetime. Put it as a note on my phone.
Lower yourself
Split step
Don’t look up
Extend off arm
I can actually try it for a set and post the video here.
Do you remember learning to drive? Clutch in, select first gear, little throttle, indicate, check mirrors, give way to the right etc etc
Lots of things to remember, but how much thought do you give to them when you drive now? You do it all without thinking but it was overwhelming at first. The thing is you practice these things until they are habitualised then you don't need to think about doing them, they take care of themselves. The key is to practice the right way. For example the most common way to practice serve is with a bucket of balls and to get through them as quickly as possible. Then people wonder why they serve like crap in a match. Really you need two balls, you should practice your pre serve routine -three bounces of the ball or whatever- first serve then second serve if you miss or change sides, catch racquet and split step, maybe even a shadow swing to finish it off. Then when you get out in a match you just follow the same routine exactly. This is the hidden value of the coach, they can track it for you and yell corrections without you having to devote thought to it.