I think it's understood in parallel parking situations with a blinker that you intend to park. Not the same in a parking lot especially since most don't back in.
In NYC, with so many people circling the block for 10-20 minutes, when you finally get an open space to parallel park in, unless the space is long enough to curve and pull forward into it, (which is rare,) one literally has to move forward (in the driving lane,) COVER the open parking spot while having the turn signal on, and wave people to go around you, then WAIT until ALL the cars behind you have to go around you. Sometimes you have to wait a couple MINUTES or MORE until the street is clear to then move forward and then back in.
Otherwise, if you move forward from covering the open parking space some ******* will immediately swoop forward and angle their car into the open space, even though they can't park that way.
They would eventually have to back out and drive forward and reverse in. Yet, whomever
physically has the space will likely get the spot. They will wait there for 20 minutes angled in until the other person finally leaves. It can be really viscous parking in NYC. Most parking lots will charge between $25 to $50 for a space for several hours. Trying to secure a free parking spot is not for the faint of heart in NYC.
Sometimes, even when you are covering the spot with your car, as I said in the first paragraph, you have to wait a long time as there is a person right behind you who wants that spot, and will try to wait it out, until you move forward, then try to swoop in. That's when you have to pull out your phone, start surfing and simply wait them out.
It doesn't matter how many other cars are honking their horns behind you both as you are in the driving lane.
