Is it absolutely necessary to install ridge cap shingles on ShingleVent II?

It is necessary to install cap shingles on top of ShingleVent II ridge vent.

Although the ventilation performance of the ridge vent will not be affected by the absence of ridge cap shingles, the six pre-made holes in the ridge vent are intended to hold the vent in place while fastening the ridge cap shingles. Furthermore, the ridge cap shingles are the primary method of fastening the ridge vent to the roof (nails long enough to penetrate the underside of the roof deck should be used). The use of ridge cap shingles is also important in order to prevent leaking at the gaps between the 4-foot sticks of ridge vent. ShingleVent II has been designed such that standard ridge cap shingles will fit across the top of the ridge vent and standard 3-tab shingles can be cut down to make acceptable ridge caps as well.