Yes, both options work - either one long strand running back and forth, or multiple strands running one length only and joined at the ends.
I have both, and both work well. If I was installing anymore, I would opt for the multiple strands joined at the ends. Simply because it is easier to tension the individual strands rather than an extremely long strand running back and forth. The downside is that there are more connectors to purchase and maintain.
The downside to a single long strand running back and forth, is that a break anywhere in that wire will fault the entire length until repaired.