I was given the task to brief and teach this for an instructor rating renewal with CASA. I was sceptical, but it does work.
The mathematics are silly as it went from accurate measurements to rules of thumb such as 1:60 and some of the trig was actually incorrect but the visual part of it really works and I've been teaching it that way ever since.
Although the end of the runway should be in your peripheral vision and eyes about 15 deg above the horizon for the best results.