Thank you very much for explaining it so clearly.

It led me to another question, the server I am playing on giving me a exp buff for being a new player and I will receive it until I reach level 70. Now what if I reach level 69 while playing as lancer/dragoon and then decide to level up conjurer/white mage class, will I be able to use that buff to reach level 69 on white mage? And subsequently do that for all classes or jobs?