Any todo-list system that I use MUST be able to accomplish these things:
view by category, AND view by importance+urgency
New items are easiest to add by category. (because that's how people remember things in their heads — it's easy to rattle off all the things that have to be fixed on your car, for instance)
It's easiest to decide which items to do next when viewed by importance+urgency.
If your only view things by category, and if your list is particularly long, then it doesn't matter if you put the highest-priority items at the top of each category, you still can't see all the highest-priority items across all categories at the same time.
must have both a short version and a long version
The "blinders" list is just the stuff you want to focus on short-term. It could be the top-5 items, the top-10, just today's todo, whatever.
Without this, it's easy to get overwhelmed by everything you have to accomplish eventually.
The "master" version contains everything not on the "blinders" list.
Without this, your "blinders" list eventually mutates into the "master" list. You must practice periodically moving items off of the blinders one onto the master one, if they're items that don't need to be focused on ASAP.