A more useful way of editing is to use the Star System. This allows for a graded selection of images rather than the more absolute Flag system.
This method is better for editing large numbers of images.
The editing process should be seen as a "Pyramid".
The best, and rarer, material near the top, the bulk of your material further down. Rejects and Outtakes at the bottom.
View this as a guide to how you should edit your digital material.
Images which show bad technique or processing, should not be rated without a good reason. "I like it", is not a good reason!.
Select an image in Grid View.
Go: Photo > Set Rating > Choose a Rating