Another excellent strategy.... one lantern holder and two diggers.

The trio slowly and meticulously covers a swath across the beach with lantern dude/dudette in the middle flanked by two diggers slightly ahead and on either side about 8 ft apart.

Here's another eye-guy tip.
Learn to use the periphery of the illuminated area, NOT the center. And never look directly at your light source. Gazing upon a brighter area only screws up your visual dark-adaptation, making it much more difficult to function in the darker zone for at least another 2-3 minutes if you are young, perhaps 10 or more minutes if you are old.