How important is symmetry or trace consistency in your designs?

Recently, I had an extremely interesting design-chat with a high-speed designer working for a globally recognised electronics firm.  (Cannot name names, but you’re allowed to guess…)

They raised a very interesting point: They found designs in review that would fail or were performing poorly due to critical traces and vias being drawn “by hand”; trace by trace. As a result, there were layout variations in certain key areas such as pad-trace exits, distances from signal via to pin or return, dynamic shape patterns… Once corrected the design performance improved.

We would be very interested to hear from experienced engineers to know how important you feel symmetry or consistency is in pcb design?

Do you see any specific design aspects where symmetry or consistent patterns of shapes, traces or other objects become important?

How do you overcome these challenges / with what methods?