I hate sewing seams to assemble sweaters. If I wanted to sew, I’d crawl around on the floor cutting out fabric, then sit at the sewing machine.
Instead, I like to make sweaters in the round, whether bottom up or top down. When I make bottom-up seamless sweaters, I’m going to have to put stitches on holders at both underarms on the body and on each sleeve. If I don’t have enough needles of the correct size to leave all three pieces on needles until I can join them for the yoke, I put each sleeve and the body on holders while I work everything up to the underarm joining point.