How does Netrender actually work?

We’ve been experimenting a lot with different render managers (Loki, Brender, Squidnet, etc…) and haven’t been completely happy with what’s offered. Either we can’t get them to run, or if they do, they don’t utilized all the cores of our CPU’s. I’m currently giving the built in Netrender a try, and it’s working great. We set up the the slaves, master and a client, all the settings, hit Animation on Network, and away it goes. And it actually maxes out the CPU’s, which is great! However, one thing I’ve noticed is that it takes quite a bit longer after the render is finished for the png images to appear in the directory I selected. So my question is, what is Netrender doing? Is it creating .exr files and one of the computers is converting those to .png? If so, is that the slave, master, or client that handles the conversion? I’m trying to better understand this so we can set up our system in the most efficient way possible, which would included being able to add and remove our workstations to the farm at will. Many thanks!