There are tier levels of constellation requirements. The naive approach is to organize them into Tiers 1, 2, and 3, with Tier 1 requiring one affinity, 2 requiring more than one affinity but less than ten affinity, and 3 requiring more than 10 affinity and rewarding nothing.
A more intricate approach to the scenario is to categorize each constellation by precisely how many affinity of its lowest requirement it requires. In vanilla, Revenant and Scales of Ulcama, for instance, require 8 affinity; Blades of Nadaan and Oklaine’s Lanter require 10. It’s more nuanced, but more accurate, too. A keen eye may notice that Revenant requires 8 Chaos affinity, which is the same amount of Chaos affinity required to reach any other Chaos-associated constellation, even the ‘naive’ Tier 3s (Aeon’s, Dying God, Torch, Abom, require 8 Chaos and something else; SotH requires 7 Chaos).
Eel and Lizard both reward 5 affinity for 3. Hammer, Hound, and Scholar’s Light reward 4 for 3. There are efficiencies scattered throughout Devotion, and are sometimes worthwhile choices for builds looking to the ‘naive’ Tier 3 devotions, but they are largely nonessential even in that situation. Spider is the only constellation that rewards 6 affinity (for 5 points spent).
Point being, nonuniformity results in build variability. If all constellations could be divided into Tiers 1, 2, and 3 and each rewarded equivalent levels of affinity, then there would exist some path to the Tier 3 constellations for a given build that would always be better than some other path to the same Tier 3 constellation for the same build. As it is now, that may still be the case, but it’s more unlikely as each constellation presents different bonuses and different amounts of affinity to reaching different amounts of required affinities.
In regards to single class viability, that was actually a goal of Cornucopia, and I think we’ve accomplished it well enough by breaking the mold of 38 Health/Energy points distribution as seen in the original masteries (each vanilla mastery divies up 38 points between health and energy per mastery point; we’ve unregulated that number and let some masteries reward a varying sum of points per mastery level).