Otto,
As I age, keeping notes is important for me. So I use One Note and generally type in everything. However, I use a multitude of tools. Because I use an iMac as my primary machine, plus an iPad and iPhone, I use an app called Things for personal To Do tracking. Since my development is in Windows, I use TickTick to track business ToDo tasks. I like the ease of calendaring with these two products.
Obviously if you create a personal program to track everything within your application, that is preferable. However, at this stage in my work, I don't have time to build one, nor can I see the personal benefit for me in the future relative to my work. So I simply build the info into One Note and that is sufficient.
By the way, we use the same program for our documentation, and yet I find that my clients rarely, if ever, read the manual, even when a press of the F1 key will make it open to the exact page needed. They have lots of excuses, but that never includes a comment that says the information presented wasn't helpful. It's always they didn't have time orcouldn't find the info, or "I shouldn't have to do that".
Tim