It's like saving a few cents of your change every time you make a purchase, and then using the saved cash to buy yourself something nice every once in a while, except it seems to build up even faster!
I highly doubt people actually can tell the difference between ground up bud that is kept on a screen in a 3+ piece grinder and ground bud that is isn't kept on a screen. Such a tiny amount of kief actually gets left behind per bowl, let alone per hit.
To use it, you can just load up 2/3 a bowl of ground bud with 1/3 kief, and either leave it on top for a boosted first few hits, or mix it in to strengthen the entire bowl evenly.