Marcel, think of the power lever, prop lever, and condition lever as completely independent of each other and completely ignorant of each other.
For example, if you move the condition lever to high idle, the power lever and prop lever don't change and don't know that the engine is high idle. So as stated the dead band in the power lever would be larger because you have to move it all the way to 72% before it has an effect on fuel flow. Similarly, if you have the power lever above 72% and move the condition lever, it has no effect.
Another example would be the one asked about feathering the propeller. As stated above, the power lever doesn't know you have feathered the prop, so continues to deliver the power the power lever demands, but the prop goes to feather regardless of the power lever setting, causing a massive increase in torque on the reduction gear.
Use this philosophy when trying to figure out what will happen if you move something and you should be fine.
As for normal operation, depends on the aircraft.