I don't think those techniques listed as worst are that way for everyone. I find rereading and summarizing to be very helpful in the ways that I do them. In addition to primary material (like books) going over lecture slides a couple of times or key passages solidifies it in my mind. Summarizing in terms of writing an outline of the material works well. I did that when I took chemistry. I read the book the summer before and wrote outlines of the chapters as I read them. Spreading out study sessions I guess is good, but for me it's more about frequency and tying it to something interesting. If something is interesting or notable I'll remember it forever. I still remember most of the concepts I learned in chemistry, but I've forgotten most of the formulas (even though I used them like a million times). Practice testing works well depending on the subject matter. Science, math, and language would be appropriate, but philosophy not so much. In philosophy I just read, take notes in class, and think about what I learned, and then I remember it forever.