I bought an iPad Pro (the one before the LIDAR one) with the intention of using it to take notes, and I completely failed. Combination of feeling self-conscious bringing it into meetings and using it at work, and just not being in the habit of taking notes.
In the past couple of weeks I've made a point of writing out the ideas and reasoning behind what I'm doing before writing any code. What I'm finding is I spend a relatively long amount of time at this, but even without writing code, I'm finding issues with my solutions on paper. Previously I would have just dived straight in and then gone "ah, shit" when I got to a blocking point.
It's also leaving me with a catalogue of searchable notes about parts of our system, and since I've written these notes myself they usually include gotchas that I've encountered before. I use GoodNotes 5 for this, it can search through handwritten text with surprising accuracy.
I'm going to continue doing this, I think it will take longer to see if there is any effect on my productivity, but it /feels/ like it's faster to find a bug on paper rather than getting halfway through an implementation, plus I'm building up all this reference material.