The chance of third eye being removed is based on how long its been up.
So for Instance it has say a 5% Chance to wear off on attack from 1-3 Seconds, 10% from 4-7, 15 from 8-12 etc etc (Those are made up but the its to show the gist of it)
So when a mob say uses hundred fists or you have multiple mobs attacking you theres a higher chance for multiple anticipations because its a % Chance to remove third eye not a specific amount of shadows per use =0