The question is, What is meant by phase? There is the building phase, the legal phase and there is the selling phase. But, in some projects there are separate phases that each have a separate HOA that also pays into a single master association. It is my understanding that the building, legal and selling phase do not matter. What matters is How many HOA phases the project is split into? and Which of those HOA phases is the subject located?
In my market, as an example, we have a project that I will call River's Landing. There are 7 phases in this project. They are all behind the same gate, they use all the same amenities, they are all of the same model types. There is a master association that all units pay into, but then each phase has its own smaller HOA board that handles their own specific needs, like building maintenance and building insurance. When I am in this project, and the several in my markets that are like them, I focus on which phase my subject is located. But I ignore the "legal phase" or the "builder's phase" or the "selling phase". For instances, "River's Landing Ph #7" was built in 3 building phases, has 4 legal phases, and sold in 3 phases. But when three of phase #7's buildings were hit with a sink hole only the unit owners in the 12 buildings that make up phase #7 were affected with higher insurance costs, lawsuits and payouts. The other phases, i.e., separate HOAs that cover their own building needs, were not adversely in that type of way.
I think projects like River's Landing are the exception. Very few projects actually have more than one actual phase, though nearly every project had different building, legal and selling phases. I only put a different phase other than "I" when there are actual HOA phases with different responsibilities and my subject is located in "II", "III", or "IV", etc.