It does seem that boosting the event jewelry instead of normal stuff(with the silver /gold) plus the second tier of affection(even minus the second h scenes) will get one rather far into whale maps if one does a dedicated 'whale squad', even with 5 rankers

FG Gatcha is like this... would you like to feel what real gambling is like without losing actual money? If so roll gatcha. I tend to do it for fun since I just don;t have the time to burn all the stam I could refill with them instead. I'd go for Character Slots and Equip Slots before stam refills 90% of the time.