Most efficient leveling outside MSQ.

[Iscah]

As your main job gets higher all the other jobs will receive a higher boost in EXP from the Armory Bonus.

This is not true and has not been true for years, if ever.

Your not-highest jobs get a fixed boost according to their current level. Last time I checked, it was +100% until you reach current expansion (so below level 80 now) and then +50% the rest of the way.