Gaja Kesari is among the most frequently identified combinations in modern Vedic astrology, and that frequency is the first thing to understand about it. Jupiter in an angle from the Moon is a common configuration, occurring in a large fraction of charts by geometry alone, so a reading that announces the yoga and stops has said very little.
The classical handling turns on a distinction that runs through the whole subject: a yoga can be present without being effective. The tradition assesses the strength of the participating planets before it credits the combination, and the criteria are explicit. A Jupiter in its own sign or in exaltation counts for a great deal more than a Jupiter debilitated in Capricorn or combust in the Sun's glare. A Jupiter afflicted by aspect from Saturn, Mars or the nodes is held to be compromised. Where the participants are weak the yoga is described as present in name only, and the term used for a broken or cancelled combination is bhanga.
The second qualifier is timing. Jyotisha holds that a combination expresses during the planetary periods, the dashas, of the planets that form it, and not otherwise. A yoga whose lords never receive a major period in a normal lifespan is treated as unrealised.
The atlas records these as the rules of a divinatory system, described rather than endorsed, and asserts nothing about their predictive value.