There should be a time stamp in the exif data, so you could track progression from one photo to the next as a very primitive form of version control.

My original comment was mostly meant as snark, but I've had an interviewer take photos during a whiteboard exercise for this reason.

Not often, but I've taken a handwritten diagram and converted it to paths in inkscape, andd cleaned it up a bit.

The resulting svg or png can be then added to the docs folder of a project. Works well with sphinx, etc.