Is there a calligrapher who can write regular script at a speed of 20 words per minute?

Yes, I can. Just very old. Zhao Mengfu can write ten thousand words a day. And monks in Huai Su and so on. However, it is not surprising that ancient people only wrote brushes and practiced calligraphy quickly every day (it is necessary to learn). I can write calligraphy at the speed of 20 words per minute. Write smaller and you can practice more.