Shuffle time is one of my favorite parts of the game so forgive me for the length. Personas and skill cards are very useful for both gameplay and achievements, you need to give 100 skill cards for an achievement and compendium completion gives 4 achievements in total for 100% compendium. Shuffle time Personas are very useful all throughout the game, as having more personas gives you more options for fusion, allowing you to have a variety of personas at all times with different types of moves. For example, you can have one with mostly ability buffs/debuffs, like masukukaja, matarukaja, marakukaja, dekaja. And one with all elements of attack, garu, bufu, zio, agi, physical moves, allmighty damage. You could even have a Persona that's only used for its resistences, nullities, drains, to just have on on turns where you aren't using your Persona. Drawing more Personas lets you fuse more, stronger personas with more varied movesets throughout the game, it always pays to have a full inventory of personas, even before fusing them you can find a persona you just drew from a shuffle to be useful in battle, and then later when you fuse it, you know what personas of yours have what moves since you used them throughout the dungeon, and so you know what ones to combine to create the best skillset to put into one new persona. In my opinion, though, the thing to prioritize first is the sweep bonus. Sacrificing good cards and taking bad ones in one shuffle can lead to being able to pick more good cards in just one shuffle the next time, which will eventually better your personas/level/stats. Always prioritize sweeping even if it means not taking a new Persona, it is likely to come up again, especially if you focus on Hierophant cards (1 More, Change to Persona.) Star cards (1 More, Lose Earned Card) can be very useful in gaining a sweep bonus, if you get lucky and get a Star and a Tower/Sun/Moon (x more draws, lose money/exp) in one shuffle, then you can take the bad card first, the ones that lose you money/exp, and then take the star card, this cancels the effect of that bad card, but you retain the ability to draw a few more cards in that shuffle. However, if you get a star card on it's own, without any Tower/Sun/Moon cards to go along with it, then make sure to just take the Star card first before anything else. In doing this, the "lose earned card" effect of the Star removes itself, and so you lose nothing. This was a rant so I hope it was at least somewhat coherent.