I am thankful to have experience up to the 5th jhana and so have been able to review my experiences and see almost all of the enlightenment factors, but the one factor I've never been able to understand from reflecting on my experiences was dhamma-vicaya. I knew from my experience it was a list of progression based on maturity of the previous factor, but I couldn't see how investigation-of-things was represented in my experiences when the other factors were so plainly visible, especially in the context of jhana practice, which is inherently counter to investigating anything at all, since mental activities outside of resting the awareness on the perceptions the meditation object produces reduce samadhi. But your explanation is absolutely spot on. The mind becomes clearer and naturally discerns more deeply and intuitively on the things it checks out, mining unseen data from them. I just had never placed it that this aspect of progress was tied to the investigation factor... Thanks!