This is not an accurate color representation, the real blue is brighter. This is a comparison of the knitting in the round gauge and the knitting the sleeve flat. Notice how uneven the stitches are in the bottom piece when I was knitting flat. The red sweater is a J Crew sweater that I have had for years that fits me really well. I am using it for a comparison.
My gauge kept coming out uneven when I was knitting flat. I tried switching needle sizes every other row, trying to knit tighter on one row, usually the knit row, and looser on the purl row, taking breaks and focusing on being relaxed while I was knitting, etc. to no avail. Until another SnB'er, Anne, asked why I wasn't knitting them in the round. Then I wanted to do it that way, so I gave it a try. I was very pleased with how the sleeve has been turning out.