If each probiotic pill, or serving of Kimche or yogurt or whatever, contains millions of living organisms designed to live in our gut----well, why do we have to keep consuming them over and over again? Why do we not get a living culture from one exposure?
Presumably for the same reason why we need to eat food every day... because the body is constantly rejuvenating its components, and requires nourishing input to accomplish this. Recall that the rationale for taking probiotics is to mimic the soil that Grok had consumed on unwashed veggies, etc.
Here's Mark's take on probiotics (2nd section down):
"...For that reason, I think it’s wise to take probiotic supplements on occasion. Not necessarily every day, since once these “seeds” have been planted in a healthy gut, they tend to multiply and flourish easily on their own. I’d certainly take extra probiotics under times of great stress or when you’ve been sick or are taking (or have just taken) a course of antibiotics."