This probably sounds insane to most people with a normal brain. But I keep three separate task lists, and this is all separated from things like calendars, reminders and things like this.
I have one big todo list system. It is neatly organised most of the time into projects, sub-projects and so on. Tagged with due dates, flags etc. It is managed through a plain text system called Taskpaper.
This is kind of the database or master list of everything.
Then I have a bullet journal like system in the iOS/macOS app called Agenda. I have different notebooks and templates for different things. One for work, one for going to the gym, and a bunch for personal stuff usually organised into Daily, Monthly and Yearly notebooks.
I basically use agenda for two things. I have a notebook where I write bullets for everything I do. Just to have a log of things. Useful surprisingly often. And I have template for all of my routine stuff that I do every day, every week or things I need to do before I have my kid, after I have my kid, while I have my kid etc. Plus that everything I need to deal with now or soon are added to my daily note.
In addition to this I always have either a Rhodia dotpad (or similar) or my pocket notebook. This is where I just write the 5-10 next things I have to deal with. When I run out of things on it, I update Agaenda and find some new things from there and add to it. And so on. If I for some strange reason run out of things there I look in the Taskpaper.
And I usually do the same kind of dance for work things.
It is a ridiculous system that is very redundant. But it is really efficient at just letting me file stuff away without it disappearing and focusing on what is right in front of me without getting overwhelmed.
Yes I have to update three different things. But the thing I actually use as I work as close to zero potential for getting lost in a settings screen or some dumb automation rabbit hole. I just look at the pad and cross things off and move on to the next thing. When I’m done with a page, I just tear it off (if it is a Rhodia) or turn to the next if it is my pocket notebook.