The problem with the new system is that its using your progress with the girl to make you want to spend coins as if your higher in affection for a girl and the event time is running low then you might spend or buy more and if you are frustrated you might spend or buy against your better judgement just to get the last few battles out the way regardless if its an event girl or not. The latest boss will give you nothing but affection items so the new system is pretty whack as I just got Alex from grinding for the past few days since the start and thats the most common of all the droppable girls and 5 star common girls are given from completing a world all the others are mostly 3 star its rare that any of them are 5 star so they are more so useful in pvp if you missed the top tier girls from past event or dont have a high tier girl from the slot machine.