I've tried a ton of digital workflows and systems, only thing that came close to a physical notebook was Org Mode.
There's a couple reasons why I like a physical notebook:
1. It's a good log of what you've accomplished in a day. Lots of times I'll have days that didn't feel like much happened, reviewing my notes however brings into sharp relief all the things that I either dealt with or accomplished.
2. There's something incredibly satisfying about striking an item off the list with a physical motion. Hard to explain but definitely something I've noticed.
3. It's a great catch-all that's always on you. I've found an A6 size is just about perfect for this.
4. I review each item from the previous day in the morning, carry though the ones that aren't done, strike off the ones that are. Not only does it put you in the right head-space but also you start to develop a sense for things that aren't getting completed. It's a good forcing function for knowing if you need to dig into something a bit more depth than you previously thought.
5. I tend to work a notebook from both ends. Todo/items to track start from the front to the back, ideas/sketches/anything else I take pages from the back towards the front. Once they meet in the middle I'll retire the notebook and grab a new one.
Haha, I like that!