Basically, there are 2 types of Lineage2 events.
1. Item gambling type
&
2. Item gambling + Exp boost type.
Both Freya and Fishing event fall into the category #2.
In general, all L2 events are chance based but I think for the case of item + exp boost type of event, the chance of winning is even lower.
In Freya event, with each bag opening, the player is guaranteed to win Freya scroll + Freya rose + Freya potion 100%, so I think the chance of winning other stuff on the prize list is much lower than the other NC gambling events.
So, don't beat yourself up if you do poorly.
I haven't played the event yet but I think I will play some, maybe tomorrow or Sunday, to get my annual supply of Freya scrolls.
To me, Freya scroll = Instant 100% exp rune whenever I want it.
The problem of Destiny rune is...once it's opened, it keeps running even when I am not online...making me feel like I am forced to play all day, everyday...But with freya scrolls, I don't have to play L2 like a no-lifer. It gives me the freedom to choose when I do my playing.