Reddit reviews Learn Like Elon Musk, Work Like Hell - A Brain Gains Short: Learn Anything, Do It the Hard Way, Go to Mars

I actually have a science-based answer for this. I read a book (actually 1.5 books on the same topic) that talked about different studies that have been done on learning, and one of the main thing it talked about is that you will progress the fastest at learning something if you mix in a few different subjects, like if you are practicing guitar you'll learn better to do a few songs at once. It's because you notice things in one song that apply to another song.

I'm explaining it bad but the books I read are these 2:

Shorter succinct cheap ebook

Longer more sciencey book