Have you taken a photo while someone else used a flash? The flash is also only on for a fraction of the camera exposure but you sure as hell notice when it happened and it went off close to what you wanted to depict you will just have to take a new photo.

The length of the occlusion isn't very relevant when the thing going in front is orders of magnitudes brighter than what you are trying to observe.

Example: https://imgb.srgcdn.com/5i9W2KZAXha7p27YHHR2.png?width=1024 good luck extracting any data from behind that flash.