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NEW YORK CITY-Looking back, Michael Rizzo, 30, is glad it happened. And he says it will never happen again. The senior associate at CBRE, working the Lower Manhattan market, reports that the best lesson he ever learned was from the deal that got away.

“My senior partner warned me to get an exclusive agreement, but the client didn’t want to sign,” he tells GlobeSt.com. The client was an employment firm looking for some 5,000 feet Downtown. Fresh from college six months before (Rizzo received his finance degree from St. John’s University and has been with CBRE now for six years), he dove into the assignment. “They assured me they would work only with me.”

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Well, you can see where this is heading. “After a couple of months of trying to show them every space I could, they called me saying they saw something with another broker and were moving ahead with that,” says Rizzo, who estimates he lost some 40 to 50 hours of work. (For the record, it wasn't a CBRE broker who took the assignment.)

Of course, to someone working the beat for years, exclusives might seem self-evident. But to young brokers, and for that matter to many new clients who don’t understand the benefits of exclusivity, it simply is not. But it isn’t easy to estimate how often brokers work without the safety net of an exclusive agreement. “Brokers are very guarded about their relationships with their clients,” he notes. It seems however, that non-exclusives tend to be more common in deals below the 10,000-foot mark.

“I don’t think they did it maliciously,” says Rizzo, taking the incident philosophically. And he would work with them again . . . if they signed on the dotted line first.

As for his bosses—managing director Sheldon Cohen and senior vice president Richard Levine, they seemed to take it all in stride, agreeing that it was indeed the most valuable lesson he would ever learn.

It was a lot of time lost but time he vows he would never lose again. “I’m happy it happened, and I’m happy it happened early on,” he says philosophically. “You have to value your time, and the people you work with have to value your time. If they don’t, then there’s an issue.”