If you pretend you're looking at one of the front pieces of a cardigan, for example, it would look something like the picture above. There's a big dip where the sleeve will be sewn in, and then there's a smaller dip on the other side where the neck is.
These are on opposite sides because, in fact, your arm is quite a distance from your neck.
I'm telling you this because I have not once but twice knit the front of a cardigan with the arm and neck dips on the same side.
The Bristow cardigan is going fine. Why do you ask?