I find it rare that there are more than 1 or 2 other players to start it. I still think some players fast travel and leave if they don’t see it at least halfway through. I generally will wait till there is another player or two in the area before starting it. Most of the time reinforcements arrive and completing the second half isn’t too bad. But beginning one without enough players usually turns into “Guardian Rout”. You end up taking a beating till help arrives. If help doesn’t arrive soon, then it is time to leave. You can only hold the fort so long..