In the original game you barely noticed when a character came or went, you just set up another character with the skills/gambits required (maybe grind a little for license points to allow that) and carry on.
Playing through the zodiac age - I set Penelo to White Mage, just to compliment Vaan as the damage dealer at the first time they work together.
Fast forward a couple of scenes and I am stuck without her for a long time - meaning I have to tackle hunts and a few sections of story without a White Mage (and because of my selections for Balthier and Fran - basically no magic).
As this is a different dynamic to the original
1) Which characters go AWOL and for how long?
2) Are any jobs are highly recommended to have during these sequences (so another character should hold them)