I can actually kind of see the reasoning there. To get a turbine to work efficeiently you need one side to be as hot as possible, then the other to cool off as quickly as possible, so the faster it hits the turbine before it cools off, the better. I can see why a long manifold may allow that cooling before it hits - plus you have all that much more surface area to dissipate the heat.
I'm still making a manifold for my new setup. But it will be really really short, and hit the turbochargers before they get too long.
I currently run the pipe as well. It works, but won't work as well for what I have planned.