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 0.59 monsters.
With 3 monsters you will run away after 0.89 monsters.
With 4 monsters you will run away after 1.24 monsters.
With 5 monsters you will run away after 1.51 monsters.
With 6 monsters you will run away after 1.81 monsters.
With 7 monsters you will run away after 2.1 monsters.
With 8 monsters you will run away after 2.39 monsters.
With 9 monsters you will run away after 2.7 monsters.