Brake DC MOTOR circuit
Braking by shorting depends on the Back-EMF generated by the motor itself. It only works at high speeds. At low speeds, the voltage is low, so is the short current and the braking torque.

If you need a really high braking torque at any speed, you had to reverse the external voltage, using a H-bridge – as for reversing the direction. Because that's what you had to do. And of course, a way to measure the speed so you can stop braking before you accelerate in the opposite direction.