Why is witch time duration random?

[Beldr]

Sometimes when I activate witch time it lasts for an entire combo and sometimes I don't even have time to do 1 atack

[Poseidon of Sea]

I think it has to do with how close the attack you dodged was. If the attack was still pretty far away (witch time activation wise) I think that decreases witch time

[Setnaro X]

Witch time duration is based on 2 things: the timing of your dodge and how quickly you attack back on enemies after you've activated witch time. There are 3 different ways to activate a certain length of witch time: a regular dodge, a bat within dodge and perfectly countering enemy attacks with the Moon of Mahaa-Kalaa.

Here's the breakdown on the duration based on the length of time:
dodge an enemy attack and stand there and do nothing = 2 seconds
dodge an enemy attack and then immediately attack with a combo = 4 seconds
bat within dodge an enemy attack and then immediately attack with a combo = 6 seconds
perfect counter an enemy attack with the moon of mahaa-kalaa and then immediately attack with a combo = 8 seconds