Your system will definitely tend to chaos. Choose a specific day of your week where you spend some time (1 to 2h) refreshing it. Try not to get lost in execution. The aim is to restore some navigability and sense of control.
In the middle of your daily action, your focus is deciding and executing. Maintaining your system is rarely a part of that. And in my opinion, nor should it be. Reorganizing your system will require a bit of a specific mental state, that has to do with guidance and purging and grouping and cleaning.
You don't have to do it every week, but it's good to know that, when you feel anxious or your sense of control seems gone, getting some order back into your system is a great way to unload pressure. Even if it seems to take too much time you don't have.
Choosing a fixed day works well because of the routine. Sunday night tends to be a good pick for many people, because there's no ticking of the clock, and the world is on pause. Monday morning and Friday afternoon are also typical favourites.
Awesome, thanks for a great succinct summary of the concept! It's working great for most of the time, but I sometimes get lazy with the weekly reviews, especially in periods when I'm stressed or not feeling great, and that always leads to having to do a “reboot” where I basically do a thorough weekly review and make sure that projects and tasks are up-to-date again.