Crafting for each char?
I’ve only leveled each crafting profession once.
I have 9 characters, but 4 of them are relatively recent additions, so my first 4 know 2 crafts each and the 5th is my Scribe.
In my case it works but I can think of a few reasons you might want to level the same craft on multiple characters. For example:
1) To get the XP.
2) In case you ever decide to delete a character who knows crafting.
3) More options. If your leatherworker is playing through HoT when you decide you want more Elonian Leather you’ll have to pull them out of the HoT maps once a day and then go back where they were again. Might not bother some people, might be absolutely out of the question for others. (e.g. if you’re also a role-player and the idea of them skipping back and forth to a city breaks immersion.)
Really the only downside is the cost of materials needed to level crafting (and the fact that it might make it harder to remember who knows what). So I think it’s up to you whether the benefits outweight the downsides.
“Life’s a journey, not a destination.”