Technically, at least for the neutral wire, we are required to mark it wherever it is visible. In practice, though, you'll almost never find the marking at your conduit bodies (pulling points) and boxes - unless there is a splice.
For the "hot" wires, the requirements are not as stringent.
Paul, it's a fair question you ask, as I know your side of the pond marks using three bands of color around the wire. Here. besides covering the exposed length with colored tape, it is also common to see the tape used to make a 'candy cane' stripe as it goes around the wire.
