[Russell Sobie]

I doubt they do flashes to add pressure. I did a little googling about it and found this blurb in talking about Le Man 24hour here: https://www.ja606.co.uk/articles/viewArticle/213197

"The cars must keep their front and rear lights on at all times during the race. They are allowed to flash their headlights to signal an overtaking manoeuvre, the sequence can only last for 2 seconds and no more than 4 flashes at any one time. The flashing is actually automated by a button on the steering wheel."

As far as there being a rule here against blinking your lights, there is not one. The rules are pretty sparse on SRS so basically anything the game lets you get away with is fair game... and I don't know of anything in the game that prevents flashing lights to be annoying.

The only time I do it is when I'm trying to get by a backmarker or just someone much slower than me after I've been tossed to the back of the grid due to an early incident. It isn't to pressure, but to communicate "Please allow me to pass cleanly; you are slower than I am, and you are slowing us both down."