I started using a technique that I call continuous journal. It came about as quick and dirty way to have a simple personal knowledge manager that was synced across my devices.

Essentially it is just a single long Google doc that you structure in a way that suits you best.

For example:

Use the hierarchical structure for sections and subsections down to 3 or 4 or more levels, then you've always got a useful table of contents.

Use shortcuts and 'word find cmd f' to easily navigate.

Use anchor link bookmarks to link connected sections and for shortcuts to frequently-access sections.

Create a table of your tags and tag sections/entries as appropriate.

Etc, structure it according to your needs. This technique benefits from the great usability and features of the Docs app.

I find this continuous journal technique enables you to get a nice overview by quick reading and quick eye scanning - great for learning reinforcement!

You can get to a few hundred pages before loading becomes a bit slow, but it's normally quick if you sync a local downloaded copy.

Use Gemini tools for summaries and text refinement.

Loading up your continuous journal doc as a source in a Google Notebook LM gives you increased utility.

I also use pen and paper. For the stationery nerds: Lamy Safari, 4 color Bic, Uni Kuru Toga pencil, Leuchtturm1917 Master dotted notebook, and my absolute favorite notebook - Mnemosyne 104 dotted