The test is to see the impact on whole system health, which is determined by the slowest constituent parts, not the fastest. Certainly, colonic flora has super

The test is to see the impact on whole system health, which is determined by the slowest constituent parts, not the fastest. Certainly, colonic flora has super high generation time, but the health of the system cannot measurably change over a three day period without changes in measurements falling well within error tolerance. Even if health did improve, the time span chosen is not long enough to sufficiently determine correlation, let alone causation.