are we to find the phases between any and everything, or just those things that are already in aspect?
This answer is based on how you worded your question. As far as EA methodology is concerned, you don't have to
find the phases between anything. It's all completely optional.
The whole point of the phases material in EA is, as was written in Pluto Vol 2, that everything in creation is in a relationship with everything else in creation. Phases, and within them aspects, are indicators of where in their cycles the two planets (or points or bodies) are in relationship to
each other. The sum total of all those relationships correlates to the sum total of the chart those relationships are appearing in.
The issue is, there is way too much detail in all of that for almost anyone to be able to take in and assimilate. There are limits to what we can handle. Thus, Jeffrey laid out what he called "key planetary pairs". Those are the ones that he felt revealed the most to the EA astrologer. Thus I suggest concentrating on them, at least in the beginning of learning phases. This is not to be taken as some form of gospel - you don't have to do it this way. Its a suggested starting point, at least while learning the system. Each astrologer is going to find planetary combinations that are especially significant, or insignificant to them, and as they go along they should follow their intuition on this.
The whole point of the cycle of phases and aspects, as opposed to the way typical astrology is taught most of the time, is that whether or not there is an aspect between two bodies, they are still in relationship to each other. The aspects represent Gateway Points, where either the past meeting the future tends to create stress, as its a time when we are intended to move forward into yet another unknown, or, in the case of harmonious aspects like trines and sextiles, a point of fruition, where all the hard work we have been doing reaches a pinnacle and we get to experience the fruits from our labors for a while. (The ending of those fruition periods tends to be some of the more difficult periods to release from. Who wants to go from a time when things are almost magically working back into a time of stress and having to face more things?)
The spaces between aspects are the times when we are simply in the evolutionary learning periods. This is akin to my description from the other day
to Serban about how the movement of the seasons from one day to the next is barely perceptible. Yet it is still going on, the proof being that it inevitably reaches the next seasonal change point. Those seasonal change points are the four squares in the chart, and the day to day movement towards them is like the times when two bodies in the chart are not within orb of an aspect. The shifting that is then going on between them is the necessary work/changes that lead to their next entrance into the orb of an aspect.
Here are the key planetary pairs that Jeffrey taught, in the order in which he taught them:
Sun / Moon - "the need in all people to actualize the inherent purpose for their life on a day to day basis, to give that purpose a face and image, a way of personally identifying itself, Moon. It describes how the person continuously is integrating them self on a moment to moment, second to second, year to year basis."
Moon / Saturn - "your ability to integrate your ego, your personal identity, who you are within the context of the social systems and/or culture, Saturn, in which you find yourself. The ability to establish your own authority within the authority of the culture."
Mars / Venus - "How one completes oneself through relationships"
Mercury / Jupiter - "how one establishes her beliefs, her principles, her philosophies, and creates the necessary intellectual apparatus to explain them, to communicate them"
Jupiter / Saturn - "Jupiter correlates to your beliefs and how they are in harmony or disharmony with the consensus belief patterns of the culture you are in thus, impacting your ability to economically survive. The economic issue relative to philosophy is obvious. The Jupiter/Saturn cycle has a 20-year life...".
Saturn / Uranus - "This is the most important cycle. It has a 48-year life and comes to maturity every 22 years to 24 years after its conjunction. It establishes the social tone, structure, every 48 years. The new social impulse, order, structures.
For myself, I would add Mars / Pluto to that list, and put it at the top of the list. This pair is described in detail in the Pluto Vol 2 book.
We can have discussion here about each of those key planetary pairs, if people would like that.
On a personal note, this topic of phases and aspects is dear to my heart. It was inner realizations (that came through working with clients) about the nature of phases and aspects that led to some of my first big EA "aha" moments. I'm not suggesting this will be a breakthrough area for every EA student. I am saying the significance of phases and aspects is profound in one's deepening understanding of life in creation, far beyond just the systems called astrology.
I rarely promote EA School products on this message board. I will say here, the material on phases and aspects covered in Pluto Vol 2 is about 20 percent of what is in the printed phases and aspects transcript. I'd call it invaluable for serious EA students. The Cycles of Becoming workshop DVD covers 3.5 hours of similar material captured at a live workshop. (Its fine to start with one.)