When you’re getting something new going, the difference between success and failure is often a matter of time: how long you give it before you give up. Efforts that begin with high hopes inevitably hit a disappointing sag. It’s Kanter’s Law: “Everything can look like a failure in the middle.”

In the messy middle, unexpected obstacles pop up because the path is uncharted. Fatigue sets in. Team members turn over. Impatient critics attack just when you think you’re gaining traction. Tough challenges almost inevitably take longer and cost more than our optimistic predictions.

That’s why persistence and perseverance are important for anyone leading a new venture, change project, or turnaround. But the miserable middle offers a choice point: Do you stick with the venture and make mid-course corrections, or do you abandon it? Do you support incumbents making progress even though the job is not yet finished, or do you abandon them for another group’s unproven promises?

Persist and pivot, and the effort could go on to success. Pull out in the messy middle, and by definition the effort is a failure. The issue is deciding which direction to take.

Consider this real-time case. Airtime, a video conversation platform, launched in the summer of 2012 by Napster legends Sean Parker and Shawn Fanning with much hype and more than ample funding. After a mere 4 months, Airtime has been pronounced in critical condition by media doctors because it has attracted only a trickle of users. Now Fanning has reportedly departed, and critics are chattering about failure. Famed Facebook advisor Parker claims that it is “ridiculously early” to plan Airtime’s funeral. He argues that it takes 6 to 12 months to get things up and running. I suppose that 12 months is considered almost a lifetime in the digital age.

But a year might seem short to other people. Just ask Hewlett-Packard’s CEO Meg Whitman, who has already declared that she couldn’t accomplish much in a year and needs more time. I hear woes-of-the-middle tales from all kinds of leaders in all stages and sectors; innovators getting a new idea off the ground, real estate developers facing stalled construction, companies approaching foreign markets, and CEOs leading complex turnarounds.

Whether it’s a start-up like Airtime, a turnaround, an elected official, or your own pet project, there are 12 key questions that can help you decide whether it should be shut down or helped through the messy middle:

Are the initial reasons for the effort still valid, with no consequential external changes? Do the needs for which this a solution remain unmet, or are competing solutions still unproven or inadequate? Would the situation get worse if this effort stopped? Is it more cost-effective to continue than to pay the costs of restarting? Is the vision attracting more adherents? Are leaders still enthusiastic, committed, and focused on the effort? Are resources available for continuing investment and adjustments? Is skepticism and resistance declining? Is the working team motivated to keep going? Have critical deadlines and key milestones been met? Are there signs of progress, in that some problems have been solved, new activities are underway, and trends are positive? Is there a concrete achievement — a successful demonstration, prototype, or proof of concept?

If the answers are mostly Yes, then don’t give up. Figure out what redirection is needed, strategize your way over obstacles, reengage the team, answer the critics, and argue for more time and resources. Everything worth doing requires tenacity.

If the answers trend toward No, as seems likely for Airtime, then cut your losses and move on. Persistence doesn’t mean being pig-headed.

“You’ve got to know when to hold them, and know when to fold them,” Kenny Rogers sang in a famous song about playing poker. That’s good advice for any leader struggling with change. It’s a mistake to give up prematurely, because the middle is always messy. But be sure to heed the 12 guidelines to choose between persistence or pulling out.