...it's totally healthy. He had developed a routine and set of expectations with his wife, that ensured their mutual needs for time together, and the needs of the kid, were being met. As he looked into how much time he'd need to take to adequately prepare, he first looked to cut down on something important to him without losing progress in it, which gave him most of the time he felt he needed, but still felt short. He then engaged with his wife to discuss his plan, and what he felt would be necessary for it, ensuring she was in agreement that reducing 30 minutes per day of "family time" was an acceptable decision. She was, so that's what they did.
No, it’s weird and I suspect there’s more to the story on how they arrived at this kind of system. It sounds mechanical and low-trust. Granted, I am not as ambitious as the author, but my wife and I do not ask each other for permission to do things. What we do do is let the other know that we’re taking on an extra responsibility, and specific help needed. We both work in tech and are raising two toddlers.
Does it though? "we both agreed it would be perfectly reasonable for me to ask for 30 minutes of additional “me time”"
So..."Hey, I wanna do this thing. It'll mean cutting down on our time together/require more help from you in watching the kid(s), but it has the potential of increasing how much I bring home by (X)" "Huh, yeah, that makes sense. Okay"
Not really. Let's say you're sharing chores. It would make sense to ask if your partner is okay with doing a bit more chores while you prepare for a better paying job.