30 minutes read for an article is too much. Since you like explaining things in depth, consider writing a book.

I always question how long an article should be, but then I reliase... Even if 30 mins is too much, if it saves you much more time googling around, it is worth it.

I want my articles to be used as future references, to be comprehensive and self-contained. I want them to be useful both to the complete beginner and to the person who already know most of the stuff.

After gathering some feedback I am now considering extending it to include the difference between structural recursion and generative recursion and differences between memoization and Dynamic Programming.

I think you could've kept the section on "basic recursion" short, keeping the focus on complex cases.

I.e. removing any definition other than normal & tail recursion, and shortening the "tree structure of regression" bit into 1 paragraph.

Most people do understand basic recursion and the function call tree, but fail to grasp it in nontrivial scenarios