This blood essence detection technique was actually something Feng Jun actively asked about from Ma Sanniang.
He wasn't trying to probe into the secret techniques of Danxia Heaven—if you're unwilling to share, you don't have to.
He was simply very curious about what this secret technique was all about, how it could consume so much spiritual energy, and whether it needed improvement.
To be honest, he shouldn't be concerned about Ma Sanniang's spiritual energy consumption, as they are not family, but now, as Ma Sanniang is recovering her spiritual energy, she might need to use the spirit land where his parents are, so he cannot ignore it.
Moreover, he's also interested in "needing improvement" because he's now a handy little modifier, the more he learns, the better.
As for leaking some of his ideas during the improvement process, he really doesn't mind at all—he's someone who grew up in the information age, uninterested in actively setting up information barriers.
