From the perspective of geomantic omen, why is it not good to use your own photos as wallpaper or lock the screen?

From the perspective of geomantic omen, there is really nothing wrong with using your photos as wallpaper and screen lock, except that it has no influence at all.

The true geomantic omen refers to the direction of the sandy head of the mountain stream, the scenery of the cemetery and the scenery of the villa.

These little problems you mentioned don't really affect them.