I'm an Android engineer working on an infra team, and like every other Meta E4, I am working towards the E5 promotion. Because of this, I'm spending a good amount of time building up the non-coding skills needed for the people/direction axis, doing things like XFN alignment and project management.
My question is how "all-in" should I go developing these behaviors: How much of an engineering excellence commitment do I still need to maintain? How often should I still be landing diffs?
Keep asking yourself this question after you delivered something with your engineering excellence: "How can I deliver the same impact with half of the time/effort?" You might not reach double productivity any time soon but it's good to always aim high.
Never feel satisfied with "I've done this beautifully". Always seek new approaches to something you already knew very well and prove to yourself that "what an idiot I was for being so inefficient in the past". This may sound unreal to you but it's the path forward.
I've read an engineering blog post talking about having kids. You struggled when you have your first kid. After a while, you get the hang of it and realize how inefficient you were before having any kid. Then the same thing happens again after having a second kid. "Necessity is the mother of invention."
Very often people don't proactively find ways to improve their productivity when it's not necessary, because life is good. Only when they struggle do they have to invent new ways to improve productivity. This E5 promotion looks scary from where you are right now -- holding on to the same level of engineering excellence output and adding extra direction/people output. How is that even possible without burnout? You will have to struggle for a while and then you will get the hang of it.