No you do not need to stay up for the entire fight , Just you can come into the fight for a hr and go to bed or leave. It would be continuous fight as long as you got members of your FC fighting it. What you do is find handful of the more hardcore people that will stay up for 10 hrs+, Need have enough good tanks so need them play for a hr or 3hr and 1 or 3 people in FC in charged of the invites for replacements and then just get those like fight for a 30 min to hr. heck can sleep , wake back up and still fight it. FC company can hold 512 people. Example: of a reward would be if were in the fight for 80% of the time and the boss died you get 2000 mythology stones.With a free company clear you would need wait 2 weeks to do it again get that 2000. If were in the fight for 1% 30 minutes and your logout or on you would get 30 mythology stones or philosophy stones.