Assuming all characters have 20+ luck...
With 1 monsters you will run away after 0.28 monsters.
With 2 monsters you will run away after 0.59 monsters.
With 3 monsters you will run away after 0.93 monsters.
With 4 monsters you will run away after 1.22 monsters.
With 5 monsters you will run away after 1.53 monsters.
With 6 monsters you will run away after 1.83 monsters.
With 7 monsters you will run away after 2.1 monsters.
With 8 monsters you will run away after 2.41 monsters.
With 9 monsters you will run away after 2.65 monsters.