When exchanging shards, the user may select up to the required number of Fighter Shards for unlocking until the next Seven Stars of the fighter.
However, if the user is already in possession of the required number of Fighter Shards for the release of the Seven Stars. note that the selection bar for the exchange number of shards can be set up to the max number of Fighter Shards you have in possession
With this, it would be much appreciated if you could check first the number of shards that you need, before going to the exchange screen and perform the shard exchange.