That came up in a thread in Bonfire I think a couple months back -- but the thread didn't attract much attention.
It does suggest that eye movement (shifting the angle of gaze) is useful to avoid having the brain lose track of small objects.
But it does involve large areas of movement making objects that are not moving on the focal plane disappear.
So exactly when this issue is most likely in the skydiving context is unclear to me. We might have situations where everything is not moving. E.g., background sky & ground essentially not moving, and a canopy on intersecting collision course with no relative movement. But then if we are turning to create a moving background, other canopies in the sky would also tend to move across the visual field. So it is harder to find cases of large areas of movement combined with small non moving objects.
Still, it is an example one of those visual problems (like plain old foveal vs non foveal vision) that can be minimized through the use of continuing brief eye movements, stopping at different points while scanning the the sky around.