Is there any advantage to overfill the transmission ?

I've been reading people adds a quart extra to the NV4500s and NV5600s

 

my friend had a 95 with the nv4500 and had gear noise in 5th and adding a second quart or parking on a side slope and filling in as much as he could quieted it down. I think that's mainly why they overfill them.
TNutcher

 

Quiter and better lube.