Why a partial seam?
 

I'm sure there's a simple answer to this. I'm making blocks with a border and the pattern says to start the first piece with a partial seam, and then to sew that seam down as the last step. But why? Does it look better? Avoid some problem? I don't mind doing it, I just don't understand why I am!

When I have done that it is because the rest of the fabric that abuts to that piece is not there yet. It is applied later in the process. Then you can comeplete the seam.

It's easier than having to stop a quarter inch from the corner where the last border will meet it. It allows you to sew on the last border all the way to the edge, then come back and sew your first one all the way to the edge.

Usually when there is a partial seam in the instructions it's because you would otherwise have to unsew or do a Y-seam or a set-in seam at some point further down the road. If you read on in the instructions, you should discover why they're telling you to do that partial seam. It does seem a little awkward at first with that piece only half sewn down, but it makes sense in the long run.

I made a quilt with blocks that said to do that. It was a square with strips around it. First strip was to overlap the last strip. Just do as the instructions say and you will then understand.

It's true, it's making more sense as I do it. Thanks for all your wisdom!