I'm still new at this so.... I don't fully understand the entire theory behind 70/30 grinds but since re-turning my knives back to a 70/30 edge they are insanely sharper and feel as if they stay sharper. The video that made me understand the differences and start to look into it is
The 70/30 edge is actually ground into the blade when its made/fabricated. I found keeping the factory edge of 70/30 gives me a longer edge retention.
I reassure you the video I posted has lots of information about knife edges and different kind of knife grinds, that'll give you an awesome basic understanding behind knife edge grinds specifically japanese knives.