Its just WAY TOO MUCH. Even if it were lower to 1000, it would still be a lot and like 3 years.
Again, you're pretty much meant to run this more than once per day if you want to finish it in any reasonable timeframe.

I'm at 280/2000. The worst one is Odin, haven't finished it ONCE in DF since mentors thing started. Not only half hour wasted every time but also no roulette credit because of disband. And can't really 'mentor' undergeared new people how to do higher dps when Zanetsuken ends at 20% boss's HP. They need to add echo to this if they want to see any results.
Every time I've gotten Odin on this the DPS wasn't the problem; lack of skilled healers were. It's a fairly healing intensive fight.