Watering: how dry?

[BigD13]

@Emilya Your answer got me to thinking; if mycorrhizae had to be kept moist, then why is stuff like Great White mycorrhizae so popular? I did a quick search and found several articles stating that they don't. In fact one article states:

"Dry formulations of mycorrhizae have a typical shelf life of 16-18 months although two years is not uncommon."

https://jhbiotech.com/docs/Mycorrhizae-Article.pdf

Thanks for you informative response.