It took me 20 hours I want to say all told to finish my Black Mage Atma. So if it is doubled, should only take 10 hours, but that is naturally really variable. It took me like 8 hours for one Atma and on average like 30 minutes for any of the others. More than likely, it will be pretty quick now, relatively speaking. I'll probably try for my White Mage after 2.4.