If you gave it a Immunity you would still have people complaining. Also you might simply dont know how long they have already waited anyway. Maybe your hunting ls got it the last and they have already waited 10 minutes. I know it might sometimes be annoying to get there and its already death but at the same time if you are not out actively hunting then do you even have a right to complain? I only feel for those that spawn it but then have someone else ninja pull it but at the same time those spawners are already there.

In the end you wont find one perfect time either. I had a discussion with a friend who is a LS leader. He said that people should wait 10 minutes after calls for ARR S ranks because without flying it might take time. I said 5 minutes should be enough and even went ahead and rode through Coerthas and needed around five minutes for a complete circle, so enough time to get there.

If there are enough to kill it then it was enough time.