Dedicated Wright almost eliminates the time needed for crafting. You can have more than one if you need it.
Not that there's any benefit to it as you are still considered to be crafting the item, so only one provides any benefit (the others could work on making mundane stuff, though).
ECS285 "He may then leave, allowing the wright to carry the process through to completion."
You are not considered to be crafting the item. You do not have the spell(s) spent, you are not required to rest. And there is no limit to how many you have.