I wonder if when you say block letters, do you mean hard writing?
As a beginner in calligraphy, this question is very confusing. Compared with regular script, running script is more flexible in word form and frame structure. We know that running script also pursues the rapidity of writing. In order to be more beautiful and more convenient to write, the running script has adjusted the stroke order of some characters. So this difference exists not only between running script and regular script, but also in different running script works.
I hope it helps you.