To duck or not really depends on the type of helicopter. Some years ago, I and another pilot were assigned to transport a group of "suits" around the Scott Paper operations north of Mobile. We parked next to one of Scott's Kaman K-Max logging helicopters. You've seen them. Two rotor heads and the blades mounted on a bias so that the two rotor heads mesh together like an egg beater. It had a big notice painted on each side that said to "only approach/depart to the front." 12 o'clock. lots of Clearence when the blades are fore and aft, not so much when the blades are at 3 or 9 o'clock.
Trivia pause: Why was Charlie Kaman's aircraft factory called the "Kaman Guitar works?"
We provided a Sikorsky S-76A to the inspection party. Hot day. High DA. Full load. Tight LZ's amid the tree farms. The new owner was aboard. Al "Chainsaw Al" Dunlop. He had just bought Remington Razors and "parted it out." Doing the same for Scott. Always scowling.
We gave a detailed briefing to the 10 or 12 passengers and emphasized that approach when the blades are turning MUST be at 3 or 9 o'clock. We loaded up while shut down and held everyone on board till the blades stopped. The S-76 has a fwd cant to the rotor mast and tip path is lowest at 12 o'clock. Pilot must hold full aft cyclic when idling. To the point of mast bumping.
Most of my SK-76 ops were offshore Gulf of Mexico and many times were to vessels. At times under way. Because the lowest point of the rotor tip path plane is 12 o'clock. Approach and depart to 3 & 9 o'clock ONLY. It's written on the nose similar to the K-Max. Despite being briefed, this 6'4" gent wearing cowboy boots decided to conference with someone on the deck, 12 o'clock under the tips of the idling rotors. You guessed it. It knocked his Stetson off and grazed his head. Concussion.
The b.s. between incoming and departing passengers is discouraged because if anything goes wrong, it a crowd killer.
One of my favorite movies is Deepwater Horizon. And that is just what is shown in the opening scenes. In real life Transocean (owner) would not permit it.
BTW, the tailrotor on a SK-76 measures 6'8" from the bottom of the TR blade to the deck. Don't know of any TR injuries with this type.