Imo, if you have a class to level 15, it should be automatically 15 when you make a new character. That way you can focus leveling a class up and don't have to level all the cross class again except to 26 and 33 etc.

Leveling blm to 26 when I have one at 50 on my main, and arcanist to 33 is the only reason my Alt isn't 50 yet. I really dread leveling blm to 26 again lol and don't even want to think about eye for an eye. So I'll be a level 50 whm without eye for an eye for a long time.