Aside from my photography, I have been lucky enough to work with some very talented set designers. When designing a set for a play, the tradition when it came to performing on a proscenium arch stage where the audience are head on, was to concentrate on the infinity point - an imaginary spot upstage centre. This made sure that any set designed for such a stage took account for sightlines and made the director's job of ensuring the focus of each scene was staged so that the audience were helped, rather than distracted by, the setting.

When composing a landscape photograph in particular, having an imaginary infinity point can be a help. We all know the rule about horizons two thirds up or down the image, not dead across the centre. And many photographers work to make the eye flow along the diagonals as well so that the potential horizontal/vertical stranglehold is broken in interesting ways. A good photograph guides the eye, creates a 'sightline', but should do so in a way that the makes the point of attention obvious without taking too much away from the detail in the rest if the image. That detail is, after all,  the context that gives the focus its point of reference. Too much detail and we lose sight of where the eye is being guided. No obvious focal point, especially in the foreground, and the landscape can seem too empty and we lose our sense of size and distance.