In my workflow specifically, I regularly reject images (done easily with a quick click of the X key), which keeps them in the library but slightly ghosts their view—perfect for helping to pare down images in order to eliminate the blinks, for instance, or other subpar images. But rejecting alone doesn’t make the images disappear from view. For that I click the corresponding flag icons on the filmstrip toolbar to hide all rejected images from view. They’re still in the library, but I don’t have to see them or work around them.
I use this tool in this way all the time. In fact, it’s my preferred method for viewing images in Lightroom, with the image files I’ve rejected hidden from view. But every time I change from one project or folder of images to another, the view resets to the default—which automatically shows all the images in the folder. Thankfully, this can be changed in order to create a new default.
To make your preferred filter settings stick, look for the padlock icon in the top right of the image display area. If the lock is open, the filter will reset each time you move into or out of a project. But with the filter applied as you’d like it (say, hiding rejected image files and viewing only flagged and unflagged images) click the lock so that it appears “locked” and you’ve created a new default view—showing your images as you like them, in my case without those rejects included.
Perhaps your preference is to mark images with star ratings or color codes. That works too! Whatever filters you’ve applied to the view, you can make them the new default view so that as you switch between catalogs and folders, you won’t have to manually reset the view each time because it will already be set for you.