Although I am not a fan of early voting, this is a very broken analogy:
Francis Wilkinson, a journalist who became a Democratic campaign consultant and is now a member of the editorial board of Bloomberg News, says, "You don't have a jury decide a court case when it's just three-quarters of the way through. New information arrives every day."The big difference is that serving as a juror is an inherently closed-ended process. There is a most definite end. The date of an election is rather arbitrary. There is no process or science behind the length of the campaign. So 3 weeks more campaign exposure might randomly change a few minds either way, but there is no particular reason to identify those 3 weeks as crucial.
In a different system, 3 weeks might be a material portion of the campaign. I have heard it said that British elections typically involve about 6 weeks of campaigning..But in campaign seasons whose length is measured not in weeks, or even months, but in years, it is silly to think an arbitrary 3 weeks more matters in terms of the additional time.