Always been somewhat confused about this, each gang has seperate "sets" but no actual hierachery or organization. You read about some sets, such as the Rollin' 60's who have about 1600 members, which seems far too powerful and you never read about one such person being head of that set. If there is no hierachery offering protection to its members and each set has different factions within it that no have no contact with one another, whats the point of being in the gang if there are no clear benefits?