Sock Gusset

My sock pattern says to work the heel for a total of 21 rows.
Then I turn the heel. My problem is the gussett. The pattern says to pick up and knit 11 sts along the side of the heel. Why are only 11stitches picked up if there are 21 rows? I did try to pick up every other stitch but it still didn’t come out right. I probably wasn’t doing it correctly. Help! What do I do/how do I do it?
Thank you to everyone who responds.

Sometimes the heel pattern calls for slipping the edge sts and then picking up in each slipped st. If not, just pick up about one st every other row (this doesn’t have to be precisely spaced) and you’ll be fine. Here’s a video on turning the heel from KH which may help

Sometimes you pick up an extra stitch to help close the gap. That hole in the corner is a problem a lot of times so I always pick up an extra stitch myself.