Shaping armsholes and shoulders

I’m working on my very first garment, a cropped vest pattern by Bernat.

I’m up to “Shape Armholes: Cast off 4 sts beg next 2 rows.”

WHY am I not casting off 4 stitches on the ends as well to even out the row?

All sweater patterns are written this way because you can’t cast off at the end of a row. You’ll have a loop with the yarn attached on the outside edge.

Don’t worry that they won’t be ‘even’–every sweater is made this way and it makes not noticeable difference.