Assuming all characters have 20+ luck...
With 1 monsters you will run away after 0.27 monsters.
With 2 monsters you will run away after 0.6 monsters.
With 3 monsters you will run away after 0.92 monsters.
With 4 monsters you will run away after 1.22 monsters.
With 5 monsters you will run away after 1.5 monsters.
With 6 monsters you will run away after 1.82 monsters.
With 7 monsters you will run away after 2.13 monsters.
With 8 monsters you will run away after 2.37 monsters.
With 9 monsters you will run away after 2.67 monsters.