You can't hold al those cards till you have that combo, you need 10 cards for it 
You only need 8 for a shieldless pvp otk though: dragon + dragon (doesnt matter which one, so long as you have the quanta for it) + sky blitz + 4x snova + sky blitz = 104 dmg
But then you have to rely on it that the 8th card is the card you need
Yeah, but you have to do the same for instosis (dragon + mitosis + 4x SoR + sky blits + chimera = 8 cards). Still, I agree that it's not the most efficient way to score an otk, since shields with 2 defense or hope, bone shield, dim shield, etc. stop it dead. Perhaps PC is needed?