In traditional process: For automotive Industry machining of air vent takes around 3-4 week in soft tooling.
However, to 3D print these parts without using any fixture and assembling take 2 to 3 days & helps reduce the prototyping cost to 1/10th.
Are you talking about the time it takes to create a mold for injecting molding? I used to work on those machines back in 1998 and it was so time-consuming! Plus the amount of money it takes for the mold is over the top most times! It makes much more sense to 3D print on so many levels.