Time balances out with points with all bosses except Vanguards. So if you did a long raid without vanguards and a short raid without vanguards it would be awarding you the same points per minute. Due to vanguards being annoying and healing up if you mess up and keep having to wait for their cycle changes etc you lose lots of time for being rewarded low points.
The only time long raids would be worth doing is when it gets turned into Jessie's suggestion being a Challenge mode awarding double points, but mistakes leading to death leaves you with no points. Be good, get rewarded for it
