On my primary account I actually completed the core story on all 9 characters/professions. But from there on (Expansions + Living World) I did the story and mastery unlocks almost entirely on my 2 "Mains". Sometimes following up with another character, if I was missing an important achievement, e. g. for a legendary trinket.

Well, I did the EoD story until reaching Kaineng (incl. Seitung map completion) for the Jade Bot stuff (and some missing hero points to fully unlock all elite specializations) on all 9 characters/professions on both accounts.

Map completion is a different story. I'm aiming for 100% (at leaast all hero points and all waypoints) on all maps and all characters (on 2 accounts). Which means that I'm not running out of stuff to do any time soon.