To preface: I am a WHM main and I've been leveling other healers, I've had an interest in SCH because of their raid utility and I like the "flavor" of the Job. I know a lot of people have issues with healer DPS rotations and such(myself included), but that's not what I want to address.
SCH in particular feels a lot harder to make work in a lot of situations, especially in dungeons. Many want this job to receive a full rework but I personally think there's a much smaller change you could make to the job that would make it a LOT more accessible and competitive with the other healers especially the other barrier healer SGE:
Give Recitation a swiftcast effect on Adloquium/Succor
SCH lacks the tools to deal with situations when things go real south in a hurry, such as if the tank doesn't mitigate properly, or if the dps take unexpected hits right before raidwides, etc., unlike it's peers which have plenty of great "oh sh-" buttons. (Haima/Panhaima, Benediction, Tetragrammaton, Essential dignity, Celes. Intersection).
Adlo/Succor have very long cast times/large mp costs, and in certain situations you feel like your running very hard in place just to barely not break even. But if (on a 90 second c/d) you could clutch crit shield to give yourself some wiggle room or prep for big damage, you could still be proactive like how the job is meant to be while not just completely negating every problem you come across. There's still the element of resource management on the c/d of Recitation.
I'd love to hear thoughts on this from people who play SCH, I feel like this change wouldn't change the feel of the job too much or make it too easy, but would be a pretty solid boon to dungeon healing and accessibility in new fights.