Is that equivalent to 15 grams of dried mushrooms? If so that is a serious dose (over 1/2 an ounce!), there would be breakthroughs and breakdowns happening left and right given that amount.
Seems unlikely that participants (particularly first timers) would ingest such a large quantity, even when spread out over a number of hours.
Perhaps if one only drank the tea the effects wouldn't be as extreme as both drinking the tea and eating the remnants, but still, I'd have some concerns if the facilitator presented 15 grams to me and said something along the lines of, "now don't worry, just drink the tea and eat the rest, everything's going to be just fine [after you get through the maelstrom phase]" :)