For how long Yakchal will stay in her room?

Question

After summoning the boss Yakchal from the sarcophagus, this one remains in her chamber full of ice monsters for some time. Do you know how long?

Are these times always the same, or do they sometimes vary?

Answer 1

I have never tested if she disappears but, many times I have waited with the boss for like10-15mins.

Answer 2

From personal experience with Yakchal, she despawns 10 minutes from the time she is released from the confinement behind her sarcophagus.