My tailoring classes have changed the way I look at sleeves. Look at the jacket in the photo above. Do you see how smooth the sleeve cap is? Notice how the edges are rounded at the top of the shoulder. The sleeves hang with no folds and curve slightly towards the body. In tailoring there are many things done during construction that create these details. Most of them don't apply to knitting but I still use the tailored appearance as my gold standard when I'm designing a sleeve cap.
Sweaters in patterns are usually modeled on tall slender people who really may not be the size that the garment was intended for. Many of the details I'm showing you are not the fault of the designer or the knitter, they are just examples of poor fit, which is the relationship of the garment to the body or the relationship of the garment pieces to one another. Correct fit concepts change over time. These garments would have been considered very fitted in the 80's
|The ripples indicate the cap was for a heavier arm or is too big for the armhole|
|The sleeve cap is perfect but the armhole is too deep or to shallow creating a little pouf at the underarm|
|The schematic showed a set in sleeve but the shoulder line is way below the corner of the shoulder. However the neckline is standing away from the models neck and the top of the sleeve looks too loose so, this is just too big.|
I'm showing these examples to you purely as an exercise in educating your eye to good fit for your own garments. A tip for figuring out what is wrong with the way a garment fits, is that folds in the garment often point either towards or away from the incorrectly fitted part of the garment.