When building decks I often have a core list of cards for the deck shell and then a pool are cards that make up the rest of the deck. As I play games and refine the deck, I move cards in and out until the deck settles into a good place in the meta.
It would be nice to have, in addition to the Sideboard, a "Maybeboard" or similar so I don't have to keep track of the other cards manually. There are other deck builders that allow for this and it's quite helpful and time saving.