The app is only downloaded once every month or two for the usual updates. It happens in the background when you aren't using your phone anyway, and by default b

The app is only downloaded once every month or two for the usual updates. It happens in the background when you aren't using your phone anyway, and by default both OSes will wait until you're on wifi too. App size doesn't matter much in the actual use of the app, especially if you're using it often.