When I first learned to make set in sleeves, (in 1948!), we pinned the top of the sleeve cap to the seam line. There usually was a notch there, pinned the notches on front and back, then put pins in all around the cap of the sleeve, dividing in half each time, adding pins until they were about 1/4 inch apart, and then sewed on the seam line, making sure there were no puckers. A little steam and a few rubs with a thumb nail, and the sleeve was in perfectly with no pleats. I was very grateful when I learned to sew two rows of stitching around the top of the sleeve to gather in the top. A few less pins to pick me!
I raised four girls, and wore out my Singer ruffler. In 1978, I started square dancing, and the most fun thing about that was making all those beautiful skirts, with lots of ruffles. Sometimes I sewed ruffles onto the skirt in one step. I'm still wearing some of those ruffles, as I still square dance every chance I get. I love making ruffles.