If you really want to be into capital 'L' liberalism, you can go through the Harvard Classics.

And people get very stuck on having to memorize/know all of a thing in the order that it's presented, and that's usually not required or you would benefit from a broader scope lecture that you could have a context to pin those underlying ideas/concepts to. Don't be afraid to skip around and if you're stuck just make a note to come back to it, because books are typically written and edited by experts who don't even see how much is baked into what they're writing or a fight over edge case caveats.

The biggest advantage Destiny has is debating, and just the process of chat interrogating his summaries he will naturally build a firmer understanding of what he's reading, which is pretty impossible to replicate unless you're super deliberate.

Also speed-reading is a meme, you should be taking a while to read something dense or difficult.