Speedreading is all about skimming well
Even when Speedreading is not a viable learning technique, Failed ideas can be repurposed. In this case, it can be repurposed as a skimming technique. The fast reading speed but lower comprehension fits the description of what skimming is all about. Thus, the following uses make speedreading a fitting tool.
A picture and keyword walk of a chapter in a textbook. Very useful for advanced reading.
Extracting ideas in a rereading. A beneficial tool for filling details once you already know the main idea.