Having some trouble seeing the utility of SCH Emergency Tactics outside of very specific situations. Let's start with my understanding of how it works.
Let's say Adlo heals for 1000 and applies a damage shield for 200. With Emergency Tactics, that turns into a straight 1200 heal.
As far as I can see, that is straight up worse than 1000+200. If you need less than 1200 to heal someone to full, it's wasted.
Of course, the name implies it's for emergencies. But even with someone on very low HP, the heal+shield is the better solution. It's functionally equivalent (enemies need to do 1200 worth of damage to reverse it), and allows HoT ticks and other direct heals to heal the target back to full, potentially still having some damage shield left over. The only situations I can see it being useful is if you're grouped with an AST*, or need to specifically heal someone to 100% HP and don't have anything better up (DRK Walking Dead, various debuffs that clear at 100% health, maybe right after a groupwide reduce to 1 HP with the other healer on the floor, Indomitability not up, etc.).
Does that sound about right or am I missing something here?

*Which leads me to another question, how exactly do damage shields stack/not stack? For the ones that do, is it a simple first in, first out?
For the ones that don't, will a larger shield overwrite one with less HP remaining, or does the one that's cast first have to run out before a new one can be applied?