They alternate between the two sections, so they do one stack every 2 hours and you can see how much labour, 2 man less than 5 mins. Remember, this isn't how they run it all the time and it is the backup system. With that in mind, most backup plans for anything if not a like for like, are always more intensive. Compare writing a letter by hand too sending an email in effort and this, for me, this looks way easier.
Worth noting that even in the vid, you have crew members of senior rank watching on as they have never seen it done before, which indicates how uncommon it's usage is.