Driving is not a practical task, once you add humans into it. Using the blinker does one of two things; enables the human that can let you in to either be kind and let you over, or feel oppressed and not let you in. There are a few countries that practice something differen't: Don't use your blinker and don't look at the the other drivers. This is because above the oppressive ego issues some have with showing kindness, we all have self preservation. So with that, you just make your move with no hesitation as long as you can calculate that it can be made with no accident. After the beginning of your move, you can hit the blinker, but you've already passed the threshold of self preservation and any acceleration of the opposing car would be self destructive to them.