Continuous ridge vents are more effective than box vents since they are installed along the entire peak of a roof's ridge. They allow warm air to escape from the attic and create enough suction (vacuum) to work constantly. You only need to install one unit, and they blend into the roof's architecture.
A boxed vent will sit on the roof providing localized ventilation only, sometimes the vacuum they produce is not enough, so you need more than one box, and as such, they clutter up the roof.
Bottom line, continuous ridge vents are perfect for shingled roofs, Ridge vents will run along the length of the shingle and replace ridge shingles and tiles. Box vents work best with flat roof structures and require a hole in the roof to fit over for effectivity.