Sort-of.....
Braking harder also gives a higher rise to the bus voltage, requiring a lower resistance to drain off excess energy faster....... otherwise you bus fault.
Remember, if you brake slow enough, maybe you need NO resistor. That is because just the switching action of the IGBT bridge circuit drains some current off. The faster you stop, the faster the rise of bus voltage, and the more likely you need a lower value resistor to hold the voltage down.
The lower resistance needed to drain the bus faster also may need to be a higher wattage.
That is ASIDE from the duty cycle......
In fact, the faster stop, *unless it shortens the overall cycle*, may have little effect on "duty"..... because the dumped energy stored in the rotating parts is the same either way. But one way it almost ALL goes in the resistor, the other (slower) you may not need any resistor. To that extent it may need a larger wattage.
Every time you stop, you dump energy. The more times per minute you do it, the larger braking duty is, and the more wattage is needed.
Most controllers ONLY dump when the bus goes high, so they are sensitive to rate... slow stops maybe don't trip the dumper, fast maybe do, low energy stops don't, high energy stops do.
The "braking resistor" does NOT stop the motor......
Modulating the IGBTs does the stopping.
The function of the resistor is to waste the energy that was dumped back onto the high voltage DC bus by the stop, so as to avoid a bus fault. That energy shows up as charge on teh bus capacitors, and raises the voltage.