Originally Posted by vithzeral
I think the roadmap should have a warning about the voluntary checkpoints. If you reload one then you will lose any earlier progress in the level (i.e. before the checkpoint!) like evidence collected; anyone you killed or disabled will also come back to life so I'm pretty sure this messes with challenges too. I would have thought this was a bug, but apparently that's the way it's supposed to work.
If you are just collecting for the sake of an achievement you dont need to re-collect it. As long as it shows in the menu in the progress bar.
It only gets reset for the sake of having a perfect score, which I find really useful if you know how to play it right