I've been playing for a long time, and have quite a few alts who have naturally progressed through the MSQ. It's super daunting now, but very doable (my latest alt completed ARR-ShB in about two weeks. Seems to get faster each time). I know a lot of people who maintain a bunch of characters at once, and once the MSQ is out of the way, it's actually very nice to be able to bypass the weekly lockouts for gear.
Each of my characters have their own theme and they center around a cluster of jobs, so not just one. I have consolidated roles and jobs into themes where, say, my scholarly character plays BLM/WHM/SMN because it makes sense that they'd dabble a bit in all of those studies. One character per job feels kind of excessive to me, personally, but chase your bliss!
In addition, I would suggest putting them all in the same FC. You cannot give items or gil to yourself, and being able to swap things around in an FC chest is key. I only have one master crafter who makes items for all my alts, and this is the only method to make it viable.
