This discrete nature of photon emission over time – temporal sampling – is key to the challenges posed by head mounted displays.
One good illustration of this is color fringing.
Color-sequential liquid crystal on silicon, or LCOS, projectors display red, green, and blue separately, one after another.
This diagram shows how the red, green, and blue components of a moving white virtual object are displayed over time, again with the eyes fixated straight ahead.
For a given pixel, each color displays for one-third of a frame; because the full cycle is displayed in 16 ms, the eyes blend the colors for that point together into a single composite color.
The result is that you see an image with the color properly blended, like this. Here the three color planes are displayed separately, one after another, and the three colored squares line up on top of each other to produce a white square. The red component doesn’t actually stay illuminated while the green and blue components display, and likewise for blue and green; this is just to convey the general idea of sequential display of color components fusing to produce the final color.