Ninety days is long enough to get past the novelty effect and short enough to course-correct before you've committed serious resources. It's the window where an AI pilot either demonstrates genuine value or quietly becomes shelfware that nobody admits isn't working.
The problem is that most organisations don't design their pilots with a 90-day evaluation in mind. They launch, they monitor loosely, and after three months they have usage data but no evidence of impact. The decision about whether to continue, expand, or kill the project becomes political rather than analytical.
A well-designed 90-day audit starts before the pilot begins. You define the success criteria upfront, instrument the system to measure them, and commit to an honest evaluation at the end - including the possibility that the answer is 'stop.'