People tend to perceive lines as continuing in the same direction.
Wertheimer's 1923 principle. Two crossing lines are seen as two lines rather than four segments meeting, which is why flowchart edges remain legible where they overlap.
In practice
- An org chart with crossing reporting lines is read as two hierarchies rather than four fragments.
- A flowchart whose arrows cross is still legible, which is why routing them around each other is often unnecessary.