wth? The 5x XP boosters get used automatically on wins?

Tao_Te_Tomato, on May 02 2019 - 17:31, said:   To make sure we're talking about the same thing, I mean "stacks" as in "multiplies," not "use at the same time."  In other words, can I effectively get 15X?    Not that "get 5X then get 3X again" off a great base XP is any hardship, of course.