It all depends on your dock and the weather. If a dock has a smooth wood pilings just use a regular fender on each pile. Some docks have concrete pilings. They will tear up your boat's rubrail. Use a fender board there. Many boards have metal strips on the other side so the wood does not get abraded.
Now you are at your dock and a storm is coming. Put down two tubular fenders vertically, use your fender board horizontally across the piling, adjust fenders so each is +/- 20% from the board's end, thus splitting the load over two fenders. If a hurricane is coming use four fenders if they will fit or use a second board. Wind and waves can put a tremendous strain on your boat's hull pushing against an unyielding dock. Use the air in your fenders to spread this across a greater area to prevent damage.