Curved arrows

I think curved arrows are better for the eyes compared to elbow arrows. In data flow diagrams, all the other elements have 90-degree corners. Making arrows curved will help viewers distinguish them easily.

In small DFDs, you may not notice this "effect". On the contrary, you may find it helpful to use an elbow arrow use in them to make the complete picture look more polished.

However, things can turn cluttered and ugly quicker as your DFD grows.

Solution - use curved arrows from the beginning or change them later on.

To put my theory to test, I have drawn two diagrams using Miro.

I was trying to recollect where I got this idea from. Cause it's definitely not mine. I went through few books and my notes and found that I got this idea while attending lectures from FH Postdam on InfoViz.

https://user-images.githubusercontent.com/2145414/118039302-0987f900-b325-11eb-825b-bc70e72104a9.mp4

From Information Visualization lectures by Marian Dörk, FH Potsdam, Summer 2020 Slide number 55 at https://infovis.fh-potsdam.de/tutorials/infovis03perception.pdf or from 35:56 to 36:36 at https://infovis.fh-potsdam.de/tutorials/infovis03perception.mp4