Americans love to complain that our presidential campaigns seem to go on forever. Between the primaries, conventions, rallies, debates and the rest, they take months, even years. Why don't we elect a leader in a month or so, as many other countries, such as Britain and Canada, do?

Many voters might think they can make just as good a choice in 60 days as in 60 weeks, but in short, they're wrong.

While a shorter campaign would save money and time, and would probably reduce voter fatigue, our long electoral process is good for voters and good for democracy. Here are a few reasons why.

Most fundamentally, a lengthy campaign forces us to slow down and fully process information about the candidates before voting. Abundant research shows that we tend to react instantly to others' words, speech and facial expressions.

For example, we immediately judge people with attractive faces, often erroneously, to be more trustworthy, intelligent, sensitive and even modest. Our 24-hour access to news, social media and the Internet feeds our quick biological impulses and speeds them up as we are constantly making snap judgments - and broadcasting them - based on new information.

Just as we often respond to an e-mail too soon or gobble down a piece of chocolate cake we were intending to save for later, we tend to react too quickly to new and salient information about presidential candidates, especially salacious revelations, policy flip-flops or inelegant remarks on hot-button issues. We judge a candidate first and then maybe fact-check them later. A lengthy electoral process forces us to wait before we can vote in a way we might regret.

Of course, sometimes quick judgments can be good. For example, we are reasonably accurate at instantly detecting human emotions, such as anger or surprise. Studies have found that we can guess which law firms make higher profits by looking at partners' old yearbook photos.

Experiments even show that people can distinguish Democrats from Republicans just by looking at faces: In one recent study, participants examined the full lips and high cheekbones of Republican congresswomen and pronounced them more feminine-looking than their Democratic counterparts.

So yes, if we had only a few minutes to choose a president, we could assess some of the candidates' characteristics quickly based on their appearance, demeanor and experience. But research shows that our decisions about people are more accurate if we have more time to think about them. Good judgment about a presidential candidate is more like a car accelerating up a long hill than a light bulb turning on. It takes awhile before we can make an informed decision.

What if the election had been held immediately after President Obama's remarks in July that "if you've got a business, you didn't build that"? Or right after Mitt Romney's "47 percent" video emerged a couple of weeks ago? Ideally, we should take time to process what the candidates say. Substance should matter more than timing. That is why the debates don't take place the night before the election.

A long campaign also generates better candidates, filtering out those who are not ready for prime time. Recall how prospective voters flitted among the contenders during the Republican primaries. Rep. Michele Bachmann (Minn.) surged in the polls after winning the Ames Straw Poll in August but was the first GOP candidate to drop out after the Iowa caucuses.

And nearly every Republican hopeful - Herman Cain, Rick Perry, Newt Gingrich and Rick Santorum - had a turn as a front-runner. If the primaries hadn't lasted so long, Perry might have won simply because the race finished before he forgot the third federal agency he wanted to cut.

A drawn-out campaign is also better for democracy because it reduces the sense of inevitability that can prevail in shorter elections. While weeding out those who can't handle the prolonged spotlight, longer campaigns also give underdogs a chance to prove themselves and establish name recognition. Just think about 2008: Hillary Rodham Clinton, the Democrats' supposedly preordained nominee, was defeated by a relatively unknown junior senator from Illinois who went on to become president.

Another benefit is that the candidates who emerge from a long campaign are better tested, more experienced and arguably more fit for the job. It's one of the longest, most public job interviews because the presidency is one of the most important, most public jobs a person can have. There is no obvious way to train to be president, but a presidential campaign seems to work reasonably well. As Vice President Dan Quayle said of Bill Clinton in 1992: "If he runs the country as well as he ran the campaign, we'll be all right."

Candidates become better potential presidents as they campaign. They get to know the electorate. The constant fundraising, stump speeches and polling force them to be more in touch with voters. And when they say or do things that appear out of touch - as when Romney tried to make a $10,000 bet with Perry during a debate, or when Obama said that private-sector jobs were doing "just fine" - they have a chance to learn from their gaffes and recover.

Candidates develop expertise during the campaign and become more comfortable with the unique challenges of the presidency. Ronald Reagan arguably became a great communicator by running for president four times. And Romney learned from publicly criticizing the London Olympics in July, just as Obama learned from publicly praising his pastor, the Rev. Jeremiah Wright Jr., in 2008 and later distancing himself from Wright's controversial views.

Voters benefit, too, becoming more secure in their decisions after a lengthy campaign. One of the problems with political polarization today is that people take too little time to make decisions and react purely along party lines. Even partisan voters would be better off delaying their voting decisions as long as possible. A firm election date is like a deadline for making choices: It forces us to delay, but not too much.

The office of the president has been compared to the office of a private company's chief executive. But the best corporate succession plans take more time than a presidential election - sometimes much more. Top candidates are groomed and challenged for years before the board of directors votes for the company's next leader. If we want to emulate business, elections should be even longer.

Since the Supreme Court's 2010 Citizens United decision, complaints about the influence of money in U.S. elections have spiked, and a long campaign certainly gives candidates and super PACs more time to raise and spend money. But in a faster campaign, the deluge of money would still happen; it would just be more concentrated, timing-wise. Besides, the political advertising in a long campaign isn't entirely wasteful: It creates jobs and provides at least some useful information.

We might get tired of watching and thinking about an election - in July, a Pew study found that 56 percent of respondents already found the 2012 campaign to be too long and too dull - but the exercise is good for us. Citizens of a democracy must work their political and policy muscles to stay fit.

We might demand instant gratification in nearly every aspect of our lives, but that's why a long, drawn-out presidential race is more important than ever. The seemingly never-ending campaign is saving us from ourselves - and our increasingly limited attention spans.

But I still am glad it's almost over.

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Frank Partnoy, the George E. Barrett Professor of Law and Finance at the University of San Diego, is the author of "Wait: The Art and Science of Delay."