Hiya Snow,
Generally, while it is true that any AC with reversers or a reversing prop can "powerback", in practice with most operators/airplanes it is not done for a couple of reasons...
First, your operation specifications (for part 135 or 121, thats the bible, next to the flight operations manual) must allow for it. I know at the two regionals I was at, it was specifically prohibited (aircraft will not utilize reverse thrust systems for backward movement, or something like that).
Second, its a somewhat complicated maneuver...you need some wingwalkers and a guy you really trust directing you backward. PLUS you can't just stomp on the brakes to stop, cause you will tip up on your tail. You need to come out of reverse and then use forward thrust to stop you, and this all takes time.
Third, the aircraft itself might not like it. Those aircraft with wing mounted engines (737s, 757s, Airbii) are VERY susceptible to foreign object damage (FOD) and they kick up ALOT of junk when in reverse, and all that stuff can get sucked back into the intake. The only AC I have ever seen approved for powerbacks are with tail mounted engines.
Anyway, at NWA we do powerbacks with the DC-9 and the 727 (well, while we had them, anyway). Its something that is trained in the sim, and in practice, you could only powerback from approved gates. At our shop, you need 3 people for a powerback (2 wingwalkers and a coordinator). If a powerback involved a turn (anything other than straight back), then you had to have a face to face briefing with the coordinator.
All in all, though, it is a time saver. You crank at the gate, blow back, and you are ready to go.
Very best,
Richard