I fly with a charging pack plugged into my controller so I never have to worry. I carry 6 batteries usually and do alot of hyperlapse's, the controller would never keep up.
Also it's not a "fast" charger. It simply charges three at the same time. The DJI station isnt practical for folks who are doing alot of flying.
Have you done a long hyperlapse yet?, eats almost an entire battery for a long one.