You do, but if you leave so much that 20 cars are pulling in front of you, you’ve either driving too slow or misjudged and left unnecessary space. At 15-20 mph traffic speeds, you need 8-20 feet. Ideally, cars in a multiple lane to one lane exit scenario should be zipper merging when congestion reduces speeds. Engineers model this behavior and try to design roads to encourage it.

If you do that and get angry when people change lanes in front of you, you have consciously or subconsciously decided you own that 20 foot gap. That reaction impairs judgement and causes accidents.