I've got multiple burners and a nice printer that prints directly on CDs and DVDs. My rule is that I'll replicate up to 50 copies, beyond 50, I pay someone else to do it, it just takes too much time. If I'm burning 3 DVDs at a time, and they are full DVDs, I can turn out one disk every 12 minutes with a label. That means I'm being interrupted about every 30 minutes for about 10 hours, just burning the DVDs. When I have most of them burned, I start feeding them through the printer one at a time!
That is why 50 is my limit. Even 50 is a pretty big job, but I usually have some manuals or programming books I need to read. If I had to do lots of short runs I'd hire some high school student to keep the burners loaded.
Doug