My experience is that you can shrink every single book into 1/10th of its size. I've only tried a few of my friend's books but looking at things it seems it's all the same regarding every subject. I mean how did they even managed to create subjects like gender studies?

It's always better to learn from the experience of someone who has done it and lived it. That's why I'm a big fan of Peter Thiel's writing. He seems like the only sensible person in Silicon valley.