Yeah I feel this a lot. It's my biggest struggle. I'm not trying to build a product at the moment just doing a year long deep dive into every part of the fundamentals. The aim is to hit 2hrs ~ 3hrs a night of study. The worst thing is when I haven't managed my energy levels correctly and I can only manage 1hr or 1.5hrs and I'm fighting to stay awake. It just feels like I'm losing the opportunity to make use of that time.

There is still plenty to work on in terms of managing energy levels. Most nights I can hit 2hrs but ideally if I could hit 3hr or even 2.5hrs consistently that adds up. It's not a trivial difference.