Predict the endwalker healing meta!

[IllyaPrisma]

On the other hand, SCH has four different skills it can use to boost shields.

Protraction also has the cool implication of letting SCH enhance other people's shields (Shake it off, The blackest night, Divine Veil, Celestial Intersection)

Please specify which 4 ways SCH can augment their own shields. The only abilities that they have that actually augment healing are Illumination and Protraction. Recitation guarantees a Crit, (though recitation on Excog or Indom is favorable in nearly every scenario)
Seraph adds an additional shield, so I assume those 4 methods are what you refer to.

SGE has Physis II and Krasis, with both options having higher healing augmentation, albeit a longer CD on Physis II. They have Haima and Panhaima for single target and AoE situations. And of course they have Zoe (in a perfect setting, Zoe would be used with every Pneuma, though this may not be the case). By that logic, SGE has 5 methods of boosting shields.

Also: All of your examples are correct, except Celestial Intersection, which is not affected by the maximum HP of the target (Essential Dignity and Divine Benison do not work this way either). If you are referring to the increase in healing potency of those abilities, Krasis would be more effective for this purpose, specifically with Co-Healer abilities.