I totally agree with that. Writing your own is a much better way to remember things. Have you heard about the law of threes? It takes three direct exposures to new information for most people to retain it (especially if it's boring or something you get anxious about). The more direct your interaction with it, the better you'll learn it and the longer you'll remember. Reading it the first time, using it in practice, writing it down, reading it out loud, etc.
I used this technique in college when I took economics...I thought I'd be so bored I wouldn't really absorb anything, so I read the chapters before class and highlighted key things, then wrote an outline with definitions for each one. During class lectures, I would fill in the gaps with examples or whatever the professor emphasized (this also was a huge timesaver for lectures, because I could fully pay attention instead of scribbling the whole time). My comprehension of economics was much higher as a result. Sounds like overkill, but I had the highest grade in the course out of 300+ students. And it turned out that I really dug economics.