I don't think it matters that much what distance they are, as long as they are hanging naturally, the body is in balance, the shoulders (at a minimum) are basically square to your line, and the elbows maintain that distance.
The less you 'do' during your setup and swing, the easier it is to repeat.
The on plane force of the swinging motion will 'do' a lot for you, when you are the balanced hub of the wheel and the shaft is the spoke. The elbow distance is about maintaining plane (and as Brian's artice/pics demonstrate, this is easier to do with mid body hands - bent left, flat right at setup).
The less you 'do' during your setup and swing, the easier it is to repeat.
The on plane force of the swinging motion will 'do' a lot for you, when you are the balanced hub of the wheel and the shaft is the spoke. The elbow distance is about maintaining plane (and as Brian's artice/pics demonstrate, this is easier to do with mid body hands - bent left, flat right at setup).