Yes, it's tradition and buyers enjoy choosing the shield.
The purpose is the same as the inlays one would see on a fine old Kentucky rifle. It's a sign of quality and it adds interest.
As I was getting ready to inlay this shield it occurred to me I might show my method.
I draw a center line on the scale, then a line across that so I have some references when I clamp the template on the scale. If I'm using bone or stag, I use masking tape and draw the lines on that.
Then I...
There's still time to register for this, you're guaranteed a good time! Bonus: it's located within easy walking distance to the source of the Mississippi River!