I did this and it worked from this link. It took about 1/2 hour or more to write the 50 sentences. I pushed save after last sentence and I got a perpetual (Not Responding) error for 5-7 minutes. Then it said your handwriting samples have been saved. Great! I'll have to wait and see if this has indeed improved recognition.
I write often, I take notes as a psychotherapist in session. The recognition in MS OneNote is poor, I have to do a lot of after recognition editing of my note. It's recognition is worse than Notes Plus on the Apple App store for iPad, which was not stellar either. In addition, often after writing a sentence and touching Next with surface pen, my writing palm would touch the screen and minimize this window and I would have to click on it. I would sometimes get the same as my palm moved across the page.