professional bad example

sooo, if i combined a longer back arm measurement (which you need to be able to bend your arm) with the same front arm measurement, the pattern would have a very pronounced angle and would possibly be impossible to sew up in one-piece form. and even if it was possible, there would be lots of excess fabric at the elbow when the arm was relaxed. i would be able to partially get around that by using a wider elbow measurement, though. specifically, if i only added width at the back at the elbow. and oh hey would you look at this early regency dress with long fitted sleeves (though they're almost certainly cut in two pieces - the fitted one-piece sleeve with darts is a pretty recent innovation, no earlier than the 1910s i'd say, though there's similar earlier designs that require a longer seam to be eased or gathered into a shorter one)...