* [[Spaced repetition]] seems like a [[learning technique]] with large scope for improvement. My impression is that most people use it for things like learning foreign language vocabulary and other "isolated facts" they want to memorize, and conclude that there is little scope for improvement. What they don't do is look at the "masters of spaced repetition" and try to cultivate the skill of using a spaced repetition program for understanding. [[Michael Nielsen]]: "I'm particularly grateful to Andy Matuschak for many thoughtful and enjoyable conversations, and especially for pointing out how unusual is the view that Anki can be a virtuoso skill for understanding, not just a means of remembering facts." <ref>http://augmentingcognition.com/ltm.html</ref>
* Probably many mundane skills like the skill of counting has limited scope for improvement. Most people can't learn to count many times faster or many times more accurately or to very large numbers. (At that point, they would probably want to make use of a counting device that just supports an increment operation.)
* Probably a learning technique like highlighting/underlining also has limited scope for improvement.