Probably one of my least used tools as well, but I did have a need for one when installing my used 2-post hoist. The hydraulic line that runs between the two posts is encased in a box beam, with flare fittings at each end. Not enough room to swing a wrench in the beam so had to borrow a 11/16" crows foot to tighten it back down. Most new hoists use hose but this is an older Bear brand with steel lines. Other than that, I don't recall ever having a need. My serpentine pulley tensioner removal kit came with some, probably a few applications where there isn't enough room for a socket in fwd vehicles but I haven't come across one yet.