the_dengle on 22 June 2015
They didn't spend 6 years making Smash Bros. They choose to release one only once every 6 years. Melee was made very quickly, Sakurai made two games between Melee and Brawl, and between Brawl and Smash 4 he made Kid Icarus: Uprising.
Smash 4 started development around June 2012, it was made in about 2.5 years.
