I usually knit the 2 sleeves at once but if it is a complicated pattern then I do one at a time. When I do
one sleeve at a time, I mark the number of rows so hoping
the next sleeve will be the same length!!
I know how you feel. When I was first learning to knit,
I would do the sleeves separate and find out one was too
short and other too long!!! I have learned over the years.

Hi Jjknitter, I think that is exactly where I am falling down. I need to set up a better system for counting. There were three things I had to keep track of at once, and I just didn't do a good enough job of sorting it out. How do you keep track?

I know and understand your pain. did a set of cabled sleeves like that and miscounted where the cable turns were on the second sleeve.

Now i always knit sleeves on the same set of needles with 2 balls of yarn. I took a knitting class and the instructor didn't know to do this, even for a teddy bear sweater.

I have the same problem with socks until some one told me to knit both of them at the same time too. there i was trying to figure out how to have 2 socks on the same set of dp's. had to be told to go and buy another set, for a while i tried to knit them with one inside the other. now i knit
5 rows on each sock then switch.

diggerb

Best $$$ I ever spent on knitting accessories was a row counter I hang around my neck on a piece of yarn. I have the kind you put on the end of a needle also, but I find the one around my neck is easier to just punch every time I complete a row, whether for keeping track of a pattern or to make sure 2 sleeves will be the same length.