Most of the time, initial elephant armies (The ones I think that they are talking about) Don't have alot of time to sit and rest
But yes, they should be affliction free a good portion of the time after your initial expansion.
The reason I don't feel it works is because of the naturally low morale of the Elephants and the small squad size (if you are trying to not combine them with Hypsists). This makes it hard for even a banner to counteract the morale loss. Especially since when Elephants get into the thick of combat they lose alot of morale because they have such low defense and can get hit easily.
But it's worth a try, if you are feeling brave