With three exposures, the entire sensor is exposed to filtered light. When the red image is exposed, for example, every pixel on the sensor is a red pixel. In a one-shot mechanism, there are holes in the image information. When the image is read into the computer, color values are calculated for the missing color pixels from the values of the surrounding pixels. With a regularly repeating filter pattern, aliasing can become a problem.
Some cameras have the colored pixels arranged in a randomized or rather a psuedo-random fashion.
This approach has the advantage of limiting the effects of aliasing. If higher resolution is needed and the subject is still, the camera can be used in a multi-shot mode. In this case, the array with its colored filter matrix is moved one pixel after each exposure so that full color data is captured in each pixel. A sequence of exposures is typically used.