I know your situation now, i really want to get Shisui too and i only need 29 frags for him (actually, 27 frags only since i got 2 frags of him from 20 free keys and 10 paid keys) .. But what i'm going to do is to just use free keys daily, and plan on the last day of the even whether if im going to spend or not .. But for me, i don't mind spending on this event since getting Power-up Items, Seal Scrolls and Mood Scrolls are my primary targets also, aside from Shisui fragments .. But i do also consider the facts or things for the next cycles so, specially that i'm targeting for something special (Madara5k) .. Needs to plan wisely since my resources are limited ..