We recently killed Heroic Spine after a lot of wipes and over the course of the progression changed my reforging/gemming a few times. I tried going haste/crit for extra Atonement healing (which FYI is great on this fight) but eventually I just went back to good old mastery stacking.
Mastery seemed to be the best, at least for me because as the disc priest in the group it was my responsibility primarily to shield people with the healing Searing Plasma to prevent them from dying. This seemed to be much more important than the extra damage/healing from atonement.
I also alternated between the glyphs for PW:B and PW:S and Prayer of Healing. I was using my barriers during the rolls, which are a high-damage phase but the extra healing for 10s during the roll didn't seem as vital as the extra healing from the PoH glyph and PW:S glyphs. It's worth noting that I very rarely take out the PoH glyph but I did try out this fight without it at one point because I was mostly focusing on shielding and smiting but in the end that turned out to be a terrible idea.
I'm not suggesting that there is one "correct" set of glyphs for a particular fight, but what I am saying is that in a progression fight any little extra edge you can squeeze out of your character matters. For healers the optimal set probably depends a bit on your healing comp, the fight, and your playstyle. The important thing is to TRY changing your glyphs, specs and playstyle in order to improve yourself and ultimately help your group be successful.
I'm in a lucky position that I'm very close with the other healers in my group and often have discussions with both about healing strat, assigning responsibilities and making suggestions to each other without taking it personally and we often jab at each other for positioning and spell choice.
TL;DR: Don't be afraid to change your spec/gems/glyphs reforged for one particular progression fight. Embrace it and you have a better chance of being successful.