From Mog to you: Darkhold full clear, 4 chests, 20 minutes remaining.

[Zdenka]

had a really good run earlier, finishing with 38:20-something on the clock... after like 7 botched runs in a row where luck was really just boning us hard

Seems the largest thing that affects time remaining is placement of the ghosts in the skeleton room. Can cost you up to 2+ minutes if they are really badly placed.