Black and white and impact frames
What’s the difference between black and white and impact frames? Isn’t it just impact frames but longer??
You often use them in succession, like negatives, for contrast.
Its used to convey explosive energy of explosions or when someone uses an attack/ability etc. It starts small and contained (small white on black background), and then "explodes" (turning the screen white and shadows go black).
Just increasing the length by alternating in some fashion doesn't really make for a good impact frame sequence.
Way I see it is, impact frames are used to connotate large impact by having a single color background, but it is not strictly Black and white, because there are impact frames that have been in different colors, for instance like orange for fire, yellow for ki blasts, and even red.

Black and White is another thing entirely, because it is an entire sequence, and it is strictly animated in black and white, with interchangeable backgrounds.