Another interesting question is why 11x11 teaching games did not catch on?
This is a book called 独創囲碁一週間速進法 (original method for fast improving go strength in one week) published in 1918 by 鈴木為次郎 (Suzuki Tamejiro, who was a very prolific Go teacher and wrote lots of textbooks, joseki dictionary in the early 20th century).
He argued that it was faster, and easier to learn, as well as relatively popular (he didn’t invent 11x11 for teaching, or smaller boards, they existed long before, as well as 13x13, etc. even 15x15). He even provided the simple opening example after all the terminologies and basic concepts were introduced.
As you can see, the spacing is exactly right for 2 space extension on all side, and very easy to form corner territories and extend to the “sides”.
And how this would progress, and how to score it manually (black 23, white 17)
Even handicap games, akin to tsumego-like problems (create a ladder to capture a corner)
And 4 handicap games openings, with just one space extension (again, very easy to create practice openings for a solid 1-space extension)
