Most of the time it's not necessary and you can simply run out of the AoE. Unfortunately there's not much telegraphing of the fact it's coming up so it's just something that comes with experience of the fights.
There is some 8-player content that benefits from interrupts, but typically this will be assigned to a DPS or the OT.
Later on you'll get Spirits Within, which is a Silence and, importantly, is off the global cooldown. Most of the interruptions (with a few exceptions) that you'll be assigned will use this rather than Shield Bash, which is a lot easier to manage. There are a couple of exceptions where things need to be stunlocked (Turn 5, Leviathan Ex) but these are relatively few.
