It's most efficient i ever seen. You need to mine only 32% or vein volume to see every single block of ore.
And branch mining is 33%. While 32% is a little better than 33%, it doesn't seem worth the bother to worry about a pattern instead of just mining in a line.
More to the point, I was looking for advice for mining that's reasonably efficient and not confusing. My experience with very large branch mines on Gregtech veins is that they become random swiss cheese once I've actually started removing ore, and it's remarkably easy to get disoriented, or forget which branches still needed work if I leave and return. This is particularly true if I chase ore vertically instead of confining myself to removing what's on the current dig level.
Mostly I think what I need are landmarks so I can quickly orient myself. The wider corridor Mauve Cloud is a possibility, since it's obviously and visibly different from the branches. Maybe a sign or two saying "exit that way -->" as well.