In my view, neither assumption holds up. The F.B.I. “had spent hundreds if not thousands of hours over the past year circling the former secretary, reading thousands of her emails and interviewing all those around her,” writes Mr. Comey. According to the investigative material posted on the F.B.I.’s website, those interviews included over 40 current or former State Department employees, most of whom knew something about Mrs. Clinton’s email because they handled or were aware of a variety of operational tech issues over four years.

So, on Oct. 27, the F.B.I. investigators were deeply knowledgeable about Mrs. Clinton’s email and could make highly informed judgments about what was found on Mr. Weiner’s laptop. Mr. Comey should have reasonably recognized that the chance of finding a smoking gun in the first three months when such evidence was wanting for the remaining 45 months — when the Clinton email system experienced such common tech issues as no connectivity, bad firewalls, phishing and power failures — was low at best. Because of those issues, State Department management, diplomatic security and tech staff members knew of Mrs. Clinton’s system and its inherent risks and repeatedly raised these issues with Mrs. Clinton’s immediate staff. Yet the F.B.I. found insufficient evidence to support a criminal case.

The second assumption involving the supposedly long duration of the email review was also flawed. First, by prioritizing a review of the few thousand new BlackBerry emails for smoking guns, a small number of seasoned investigators could have carefully looked at them in hours, not days or weeks.

Second, like other organizations that regularly review enormous amounts of stored electronic data, the F.B.I. possessed the technical means to determine quickly whether the haul of other emails on the Weiner laptop were backup duplicates of ones already in its possession, as the vast majority apparently turned out to be. Off-the-shelf software was available to compare the Weiner laptop emails against the F.B.I.’s existing collection to exclude duplicates from the review.

What was Mr. Comey’s third option on Oct. 27? Wait and see. Monitor the progress of the review closely. Do nothing until there was something to report.

Even a delay of a few days would have afforded the F.B.I. investigative team time to get a very good idea of what most likely was and was not in the new evidence. As it turned out, the team was able to complete its work days before the election, and Mr. Comey informed Congress in his Nov. 2 letter that the F.B.I. investigation was again closed.