The method that feels best is not the one that holds
This is the highest value correction in the whole course, and it belongs here rather than in lesson four because of what it does to motivation. Study that produces no visible progress removes the reward from studying, and unrewarded effort gets abandoned, which sends you back to the loop in lesson two.
What the research says
Dunlosky J, Rawson KA, Marsh EJ, Nathan MJ, Willingham DT (2013). Improving students learning with effective learning techniques: promising directions from cognitive and educational psychology. Psychological Science in the Public Interest, 14(1), 4 to 58 doi
Ten common study techniques rated for how useful they are. Testing yourself on the material and spreading study across days both came out high. Rereading and highlighting, which are the two techniques most students use most, both came out low.
Roediger HL, Karpicke JD (2006). Test-enhanced learning: taking memory tests improves long-term retention. Psychological Science, 17(3), 249 to 255 doi
Retrieving material from memory beat rereading it for what people could still produce later. The useful extra detail is that the students predicted the opposite. The method that feels most productive while you are doing it is not the one that holds, and that mismatch is itself the thing to know.