As many as you can handle, which may be one or none some days or weeks.
What I do recommend is having a context for all your lists, a lists of lists that connects these fearsome beasts into a shape that can be comprehended by an adhd/executive challenged brain, a tree formed from branches all held up by a central trunk (your list of your lists)!
Actually I think of it not as a tree anymore but rather the inverse movement, a river network of converging frivolous lists of small things joining together as tributaries to form a unified flow that combines all into itself in terms of daily executive function challenges.
A concrete example of this idea in digital form is org mode (which this perspective is inspired from).
https://orgmode.org/guide/index.html
Also Treesheets is a nice simple conceptualization