I saw a post online about someone practicing mental arithmetic for a month or two, and they kept track of their speed with similar problems. I was really intrigued to see how much their speed went up after so little practice, so I thought I would try a similar experiment for fun.
The site I'm using for practice (default settings)
Date | Number Solved 2020-09-01 | 23 2020-08-31 | 22 2020-08-30 | - 2020-08-29 | 20 2020-08-28 | - 2020-08-27 | 15,20,11,23 2020-08-26 | 11,13 2020-08-25 | 6,11,16