Comment by chrisxcross

I used it to integrate sketching into a web-based diagram editor ~10 years ago and it was a breeze. OK, I had to train it myself. But it takes only minutes to draw all the shape variants needed. In practice I used 6 shapes and about 5 variants per shape. I conducted a usability test and the $1 recognizer only failed to recognizes the sketches 2-3 times out of ~300 shapes drawn by different users with no additional training.