I have to disagree. Everyone that hasn't missed an event before should be able to run a minimum of +13/+13 from Mashu, BB, Mecha Eli-chan, all with School of Chaldea + support Extra class with a max LB one. Add in Arash and Shiki (Assassin), and that's +14/+14 before factoring in their CEs.
I think this adds up pretty quickly since base drops are only 2 or 3.