Secret grade is done within the confines of the game with no luck manipulation.
Note that the piece distribution algorithm is usually not a pure random() function, but one that's optimized to remove or reduce piece repetitions. For TGM it's history based (keep in memory the 4 last pieces type, reroll in case of repetition, with a 4 or 6 reroll limit depending on the game). IIRC Shuey uses a ruleset that uses the standard 7-bag algorithm (it's a Fisher-Yates with 7 elements; put all 7 types in a collection and deplete them one by one, randomly).
Secret grade is done within the confines of the game with no luck manipulation.
Note that the piece distribution algorithm is usually not a pure random() function, but one that's optimized to remove or reduce piece repetitions. For TGM it's history based (keep in memory the 4 last pieces type, reroll in case of repetition, with a 4 or 6 reroll limit depending on the game). IIRC Shuey uses a ruleset that uses the standard 7-bag algorithm (it's a Fisher-Yates with 7 elements; put all 7 types in a collection and deplete them one by one, randomly).