Part of me is convinced that whoever first came up with the set-in sleeve was a sadist. The damn things can be so mind-nuttingly frustrating! You can sit there spending a couple of ice ages pinning and easing, easing and pinning, swearing and easing, and repinning until your armscye looks like the world's worst blind date. And then comes the basting and stitching, hoping that nothing slips and moves under the presser foot.
It's enough to drive one crazy!!
It's where I keep my thread.
It's also entirely possible that I forgot to just lay the bodice open and flat and match the sleeve up before sewing the side seams. But we're just going to pretend that's not a Thing, and that it's All. The. Sleeves's. Fault!!
This is what I get for branching out on projects that require more than two pieces.