I recently returned from Africa where I took 20K images. In Lightroom I created a Collection for each of the animals as it was random what we would see each day. Using the Collection I compared animal shots taken on different days, and I set the reject flag on 80-90% of the photos. (I also set stars and colors). I went to delete my rejected photos and Lightroom wouldn't let me. I learned from NAPP that flags (unlike ratings) don't carry over from Collections to Folders. I think they should or at least provide an option to do so. Lightroom is great and this is the first time it has not accommodated my workflow, and I think it should. Now I need to figure out how to remove these photos from the Collections and/or delete them from the hard disk without having to review again.