>>93650250Toriyama's actual explanation is that Saiyans actually thrive in peaceful environments which boosts the number of S-Cells which are involved in the transformation, then the stored energy is released all at once with an explosion of anger. That's why Vegeta struggled until he settled down on Earth. Also Saiyans with a high number of S-Cells will produce children with naturally high S-Cells which is why Goten and Trunks were able to become Super Saiyans so easily.
Super Saiyan 2 and 3 are essentially overclocked versions of the basic Super Saiyan form, which is why it required that Goku and Gohan master the Super Saiyan form and draw out its full power in order to ascend. Grade 2 and Grade 3 is the process done "wrong" by focusing only on the muscle mass increase from Super Saiyan instead of efficiency.
