What's the deal with the E30 turn signal relay?

[ELVA164]

I noticed this back when I had my 2002. The turn signal in that car (and basically any other car) flashes evenly right away. The E30 flasher relay is different for some reason. When you first depress the turn signal stalk, the light stays on for 0.5 second. After that first flash, the relay clicks every 0.25 second.

Why is the first click twice as long as the others? It happens in every E30 I've driven.

[ELVA164]

Whoops, not sure why this ended up in the E46 section...