I wonder where the code for a Gasha is. I assume what you get from the gasha is calculated upon opening. Which means there is a code somewhere that has the probability and it would be interesting to at least know the chance we have of pulling on of the rare items.
Now, that I can get behind. There is a rational purchasing decision to be made when buying a gasha, and that is mostly based on several factors
a) the value of good items.
b) the likelihood that you will get good items.
c) the value and desirability of common items.
(a) and (c) we can estimate, but (b) is never known, and it would help a lot. When you play a lottery or gamble, you have some idea what the chances are. Here, we don't. Knowing the chances = more rational purchasing = happier and less whiny players.
That said, in my experience, and in some other guildies experience, bags 2, 3 and 4 are heavily weighted to the common item, 50 charges, so they score high on factor (c). That 13 dias happen to be excellent price for 50 charges, which makes those bags a good deal, IMO. Bag 1... ummm... no, thanks.