One can have evidentiary standards which don't in every circumstance require a long time period. For example, there are (rarely) medical clinical trials which are ended early because the experimental group's protocol (say, a drug or a procedure) works so well that it would be inappropriate to wait longer to give all the study participants the experimental intervention.

People who know more statistics better than I do could provide a more analytical description, but basically given the results so far, the likelihood of a "failure" (for whatever definition the city has chosen) is extremely low.