"Ewan was right for Ewan; Martin is right for Martin; Dick Miles is right for Dick Miles; Brian Peters is right for Brian Peters; Crow Sister is right for Crow Sister; Sedayne is right for Sedayne. There are no rights and wrongs here - just individual approaches all of which are equally valid."

Yes, I'd agree with that.
To return to the OP, my query concerned "how do 'you' tackle the long ballads", rather than "how 'should' long ballads be dealt with."

I think it's a case with any creative discipline, that you need to find out where your personal strengths & weaknesses lie and adapt how you personally work with that discipline, to accommodate those strengths and weaknesses.

It is interesting and helpful knowing how other people go about things, whether others prefer to perform strictly according to long-standing traditional conventions, or do things utterly uniquely, or even a bit of both.

As for instrumentation, I can see the value where the narrative suddenly shifts pace or certain events takes place like riding a long distance (which takes time, but may be abruptly dealt with in the verses), a sex scene/romantic interlude which isn't explicitly dealt with, a scene of music and dancing contained in the story itself, a long sea journey. And so-on.

But like the rest of it, I guess it's gotta come down to you being 'in it' somehow - rather than stomping on it.