Talk:Clash!! Nightmare Luffy/@comment-10336-20170901181245/@comment-30827145-20170902192935

No, mathematically, it is the same to use the books one by one or 5 per time. However, it is more expensive to use less books (because the more units you add when powering up an unit, the cheaper it is per unit).

The only case I can see where it is better to use less than 5 SB each try is when you need less than 5 skill ups. Since each can theorically give a skill up, you might find it better to not use them all. For example, if you only need 1 skill up, you can use only 2 or 3 copies and, if you are lucky and got it, you can sell the remaining ones to Ray. Note that I never do that because chances are too low and it is frustrating to not get power ups (even if you have more tries).

For the story, I've farmed FN Violet last week with natural stamina and last power up, I was 3 skill ups from max and I had 4 copies left. I powered her up and got the 3 skill ups. RNG...