Assuming all characters have 20+ luck...
With 1 monsters you will run away after 0.26 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 1.21 monsters.
With 5 monsters you will run away after 1.52 monsters.
With 6 monsters you will run away after 1.81 monsters.
With 7 monsters you will run away after 2.09 monsters.
With 8 monsters you will run away after 2.35 monsters.
With 9 monsters you will run away after 2.66 monsters.