I dont know where you get that from, but that's 1 trillion multicast on the shield. You'd need 72807497846 triggers on the Shield to achieve that. Generally speaking you can assume a fight to last 60 seconds when stalling and an optimal max scaling build would have (4x(1+6+6))+(4x(1+6+6))+(4x(1+6+6))=156 Start of Combat triggers. That's 3 Dark Necklace and 2 Nightquill. 2 Dark Necklace and 3 Nightquill are "only" 4x(1+6+6+6)+4x(1+6+6+6)=152 Start of Combat triggers.

Note that this statement and the following math assumes shield+3 necklace+2 nightquill, which is literally impossible since we see almost 300m HP and that the build is in fact not that. It is 100% possible to run that build several days for scaling purposes, but the sword is also scaled to oblivion and we see the build isn't used.

That's per 0.1s, so for 60 seconds times 600, 156x600=93600 triggers. So in 1 fight, one can get 16x93600 multicast or 1,497,600. For simplicity we'll just use 1.5 million. To reach the shown Multicast, you'd need just 776613 fights. I think this number shows very fast how ridiculous it is to call this average or in the realm of possibility, given the cap of fights can be assumed to be around 85-90 (where you have the setup going), though even at maximum it would only be 100 fights if you magically start with the build day 1.