Just wondering, how to draw this good on a sheet of paper? It does not have convenient undo feature: if u draw a stroke wrong, the entire page is ruined, especially when using a marker or pen instead of pencil.
Being good at drawing on paper (or any analogue medium, frankly speaking) requires you to train and untrain some physiological quirks in order to get the lines as you want in a single pass. At that stage, it's more or less muscle memory that's making your hand move a certain way.
It's not too different when drawing with a digital pen. The digitization of artwork is something like a safety net to undo or change those little accidents you might inadvertently cause during your session. With an ink pen, you really cannot undo those and thus left to improvise on your "happy little accidents" while you continue on your way. You just have to let it go and keep going.
Even in the year 2020, Bob Ross is still a great teacher.