Paper-based Bullet Journal method has become quite useful and sticks around, as long as I have the stamina to maintain it, and is always pleasant to return to even after a break.
@MarkG I have tried on two different occasions to keep a Bullet Journal but the first time I tried it I couldn't stick with it. I did a good job with sticking with it the second time, but I found the upkeep of it was taking away too much time. I was putting more time and effort into maintaining it than I was gaining from increasing productivity in return.
It's maybe not the same thing but in terms of keeping track of things and making sure something important doesn't slip my mind, I've taken to carrying a Field Notes Memo Book (https://fieldnotesbrand.com/products/autumn-trilogy) with me everywhere and just writing everything down. I find it's much easier to get things on paper than it is putting it into my phone. Later, when I have time, I can then take what I wrote down and file it away somewhere else. When I do, I use a red pen to leave a big check mark over top of it so I know I filed it away somewhere. As I keep everything in my memo book by date, I don't have to worry about losing anything: If I don't get around to filing things away today or tomorrow or even the next day, I don't have to worry about it because I know it's not going anywhere.