Antiochus 15 sets out the conditions for a planet being capable of arising or sinking, the outer planets are said to be capable of arising when they are between 15 to 120 portions from Helios in the 1st half of their synodic cycle and capable of sinking when between 120 and 15 portions from Helios in the 2nd half of their synodic cycle. In this situation, Helios is always the faster moving planet, he is the one determining the phase relationship between the two planets. Mr Schmidt alludes to this in his commentary on p236 "If the planet has already made its first appearance before the 15-portion interval has been achieved, it has not so much displayed its natural capacity for arising as it has been allowed to exercise its desire to make an early appearance by special dispensation from Helios.". The outer planet displays itself at the whim of Helios.
The case with the inner planets is not always the same; sometimes, Aphrodite or Hermes move faster than Helios, as Porphyry says: "The star of Aphrodite and the star of Hermes bring to completion those things that change the life of men and those that cause changes upon the earth, with a daily motion sometimes more and sometimes less in relation to Helios.". (p230) In those cases, it is not Helios that is determining the phase relationship but Aphrodite or Hermes.
I am wondering if this could be related to the odd phrase in Antiochus 5 "And that while Helios and Selene have the esteem of royalty, Aphrodite and Hermes follow and serve Helios, Aphrodite taking part in touch and desire and generation of offspring, Hermes in reason and practical wisdom."
The Antiochus 5 statement implies Aphrodite and Mercury can directly influence Helios and the changes that are wrought in the life of men or upon the earth; if you look at it from the phase relationship, which is normally determined by Helios, it appears there are times when he is influenced by desire (Aphrodite) or reason (Hermes) and thus not acting solely according to his own nature or capacity.
Does that seem to be a reasonable assumption to make?