All my good luck with pulls (two Supernovas + other much-needed units) is balanced out by me having the world's worst luck upgrading Going Merry. My Merry is only 6/10 (1.2x atk boost), but it probably fails 60% of the time or more, and has been failing consistently since low levels.
To the point that when I try to upgrade I literally say to myself "OK time to waste some Cola!"
Yesterday I failed a level 2 to level 3 upgrade on my alt account. I was like "what? you can fail so soon?"
It's probably my most hated thing in the game. I don't mind the Gacha even if I have had some terrible luck (until this Sugofest <3) but I don't see any reason why the ship failure rate is so high.
And since it doesn't make sense, it just frustrates me when I've tried >5 times to get a level up and I keep failing.