Keep the hook fastened
Fewer walks around the trailer
Throw all straps over and attach the hook before walking around to the opposite side to tension up the straps.
Perfect in windy weather
High loads and hefty winds can easily detach the hook. This is when a magnet in particular comes in handy.
The strong magnet attaches easily on any steel surfaces, so you can tension up the load without the hook loosen and fall off.