When you put a new image point it is easy to apply it to all frames, just press:
"Apply to all animations"
"Apply to whole animation"
The problem exists when you delete an image point over which you used one of the above options.
The checkpoint is cleared in the current frame but there is no way to apply that deletion to all other frames.
An option is missing to apply all the points of the current frame to all the animations or to the whole animation.