Today I tried a sewing technique that I've read about, but usually discounted, as I didn't actually believe it would help.
It's called chain stitching.
The idea is simple. You have a stack of items to be sewn sitting ready. As soon as you finish the first seam, you grab - without cutting the first item off the machine - the next item and sew it next. Repeat until all items are sewn. Now you have a series of items connected by a chain of threads.
In my case, when I had sewn the last napkin, I cut the chain off the serger, and flipped the whole thing around, and sewed the edges of the opposite side without cutting - it made a ladder of napkins. I cut them apart and then sewed the two adjacent sides, making a new ladder.
I saved 30 percent off the individual napkin sewing time. THIRTY PERCENT. I figured I'd save a few seconds. I had no idea that it would be THAT much better.
I've read that experienced seamsters do it for garment sewing. I'm going to have to try it.