How do you decide between the options for one shipment or several shipments to FBA?

I always just pick the five box option because I don't have time to package everything three different ways to figure out which option ends up being the cheapest.

The reason I bring this up is because I got a survey from Amazon asking about how I determine costs and pick my placement option so I'm wondering if they're seeing a downturn in FBA use... I know I'm not sending in nearly as much inventory these days because of these constraints