In the concrete industry, we call it a "rod", usefull both for setting the base grade before a pour, and for leveling off the poured concrete before finishing.
Anyways... I dont do paver work, but I've leveled off slab floors, and I've used up to a 15' long 2x4 with two guys on it.
Rodding/Screeding takes practice.
Just out of curosity, how many guys use a laser to check your grade heights on your hardscapes?
FYI, Power screeds exist, My company had a truss skreed like the one pictured below.
Only really usefull on HUGE pours.