Laws are written such that you have to signal for a particular travelled distance along the road (typically 100 feet) before you depart your lane. At higher speeds, fewer blinks are actually needed to meet that requirement.
For a normally paced and typical 1.5 Hz blinker frequency, it takes just 3 blinks to finish while travelling at 90 kph (50 mph) or more to meet the distance requirement. You need to allow for more blinks to finish at slower speeds before you leave your lane.
So, it's actually illegal to use just one tap of the Tesla configured 3 blinks at speeds slower than this.
You MUST do two taps, or a hold... to get more. Or risk a ticket.
All of this to say, it's just another good excuse to drive fast in a Tesla!! Yee ha!
Why can't Tesla provide all this function:
http://www.autowindow.com/orderTAP.html ?? It's costs like what, $80 as an aftermarket add-on... would be "free" in a Tesla could do all that stuff with some software changes and user controls on the screen.
Personally, I like to continue signalling after the legal requirement has been met plus some more.
If you watch truckers, they often signal at the beginning of intention to change lanes and continue signalling all the way through to the truck getting fully into the new lane. Maybe they have different rules that say they must do so...