That is not how it works. Running 20 minutes per day makes you great at...running 20 minutes per day! Again, moving around for 20 minutes a day is great, as long as you don't get obsessed about it, which obviously isn't about health. From a results point of view however, expecting to develop as a runner from running very low mileage, e.g. two to three kilometers or miles or 20 minutes per day, is far from optimal. Then its much better to increase mileage, run longer and a couple of times a week, at higher intensity and to rest a day or two every week to allow for proper recovery.
Having said this, I ended 2019 and began 2020 with a mini runstreak. Running for only eight days in a row at mostly low-intensity effort, I didn't feel the need to take a rest day. In addition being off from work allowed me to rest and recover more than usual. I ended the year with 2691 km for 2019 and if I summarize the distance I have covered running during the last ten years it sums up to 23490 kilometers which equals running 6,43 kilometer per day every day for ten years! That I think is an achievement and much more efficent as compared to if I had ran three kilometers every day without rest days.
I performed one of my regular tests yesterday running a sub40 10k at anytime during training. This is something I want to be able to do when I am 50 years-old and now at the age of 48 I was able to run a hilly and windy 39:32 10k having the Vaporfly 4% Flyknit on my feet which probably helped me run somewhat faster than I otherwise would have been able to. I felt comfortable and relaxed through five or six kilometers but the final four kilometers were a lot uphill and I added some extra hills just for the sake of it and in the end it got a bit tougher with my pulse in zone 5 but I was still able to finish the final uphill kilometer in 3:51 which was the fastest kilometer during the 10k.
It feels great to have ended 2019 and begun 2020 on a positive note and I look forward to continue along that path in 2020!