Personally (my opinion) I believe this issue has been run into the ground by Traditionalist dogmatists, in a manner similar to what we find in mainstream Vedic astrology, with the splitting of hairs relative to ramifications of definitions and variants of definitions of the descriptive terms used by the various authors. This is why I personally have adopted a simplified approach to consideration of these matters regarding dignity, exaltation, etc.
One thing I do believe: I believe the signs condition and modulate the expression of planets in them, not the other way around: in other words, I believe the signs "rule" (so to speak) the planets, and that while the planets do also reciprocally influence the signs, the strength is from above (sign) downward (planet in sign) Now, this is (historically) a minority view (although it dominated early Hellenist thought, eg Manilius, and also much of Islamic transitional era astrological thought, eg, v. Ibn Arabi's "Mystical Astrology", also the Harranian astrological works of Thabit ibn Qurra, and it also is still dominant in Jaimini Vedic astrology)
The planetocentric outlook, developing early on (Firmicus Maternus, Parasara) came to dominate astrological thought (Western and mainstream Vedic), so planets became the "lords" of pretty much everything astrological, the "power centers", and this perspective really accelerated during Western Medieval, Renaissance and Reformation times, and continued to do so in the development of Modernist astrological thought and practice.
My opinions here are, of course, highly controversial and I certainly do not want to try to pawn them off as "true", or to have any one "believe in them"; just thought I'd pass them on, from one who has been involved in thinking about, and studying about, and testing about these matters, for many years...