I was also quite skeptical when I heard, and occasionally ask others to make sure I'm not fooling myself w.r. smell. Also, if I did heavy sports in them, I may stop, even if it was just a week or two. Casual daily wearing could easily go for a month.
Good old white-colored old spice (I'm allergic to the blue colored ones) last about 30 hours.
I gather that body odor is closely tied to your own personal skin microbiome, which might explain very divergent effectiveness of products unfortunately.
