While companies' revenues have risen, the increase has been outpaced by the increase in their working capital. "What that means is that you have to put more working capital toward every dollar of revenue you're generating," he said. "That's not the result you want."

But Ginsberg said that it's not surprising the progress tailed off. "In our research, as well as the work we do with clients, we see that there's very little stickiness in working capital outperformance," he said. "Those who do very well tend to hold onto that level of performance for one year or two years. Very few are able to maintain it for three years."

The normal ebb and flow of business, as a company renews its contracts with its suppliers, adds new suppliers or strikes deals with new customers, means there are constant opportunities for working capital metrics to deteriorate, Ginsberg said. For example, the procurement group may shift its focus from getting the longest payment terms possible on its purchases to getting the lowest price possible. On the receivables side, sales representatives may try to boost their numbers by offering to give customers more time to pay. And if the sales team and collections aren't in sync, a customer with a question about an invoice might go directly to a sales person, and the sales person might resolve the dispute without consulting with collections, and in a manner that doesn't match the parameters of the company's working capital management rules, Ginsberg said.

Making headway on working capital management is complicated by the fact that the processes involved are spread over so many different departments. As a result, Ginsberg says, the key to success is the governance structure that companies put in place to oversee working capital efforts.

While there's a perception that working capital is the responsibility of the finance team, "because of the need for cross-collaboration, it's often beyond the scope of finance to rein in working capital," he said. "They only have so much influence on what's going on in different business units," he added, citing such areas as manufacturing and procurement.

In REL's view, the best practice, which is "not that prevalent," is to establish a center of excellence for working capital that includes representatives from finance, manufacturing and global shared services, he said.

Shahrokh Moinian, head of trade finance and cash management for corporates Americas, Global Transaction Banking at Deutsche Bank, said he has seen some multinational companies name a senior executive as head of working capital, illustrating the importance of this activity within the finance and treasury functions and helping to further fuel the growth of supply chain finance.

While treasurers may not be in charge of working capital, Ron Chakravarti, managing director and head of liquidity solutions and treasury advisory for Citi Treasury and Trade Solutions, said they can play an important role in educating other parts of the company about why working capital matters.

"What treasury is becoming is not the decider but the key influencer," Chakravarti said. "It understands capital management or if you will, corporate finance. It's applying that corporate finance discipline to tell the business, 'Revenue looks fine but if you look at how we're using our capital, it's very inefficient.'"

REL's Ginsberg said companies' biggest opportunity to improve their working capital lies in the area of inventory and added that he has seen an "increasing focus" on this area. But he said inventory is the most challenging aspect of working capital.

Inventory involves not only payment terms, but raw materials, the company's work in progress and its finished goods. And as companies' supply chains stretch across the world, their inventory is also far flung. "It's much more complex and therefore the management of it is much more complex, and it requires a greater degree of cross-functional collaboration than the other areas," Ginsberg said, and cites an "increasing focus" on inventories.

Bankers and consultants agree that when it comes to working capital, shifting invoices and payments away from paper to an electronic format is a plus.

"In general, any time you're doing electronic anything, it should impact," said Douglas St. Amant, senior vice president of global treasury management sales at Bank of Tokyo-Mitsubishi UFJ/Union Bank. "Especially on the collection side, if you can get invoices out sooner, or if you're doing auto posting."

Chrystal Pozin, a managing director at consultancy Treasury Strategies, noted that making payments electronically gives companies "more leeway in negotiating terms with their suppliers," as well as more flexibility in timing. "I can decide when I put the electronic payment in, whereas the check cycle runs a specific number of times, anywhere from one to four times a month," depending on the company, Pozin said.

Centralization is another way companies can realize gains, said Citi's Chakravarti.

"If you have 100 businesses operating in 100 different places, and each is doing its own way of collecting money from customers and paying money to suppliers, you're going to be a lot more inefficient than if you've centralized those processes into a few locations," he said.

A company with multiple units could move payables and receivables flows to an in-house bank, he suggested. "Ultimately that centralization of flows is what gives companies greater predictability of when cash is going to come in and out," Chakravarti said. "It's a very logical next step to do that to squeeze out efficiencies."

Read the June Special Report on Working Capital Management.

Related: Supply Chain Finance Takes Off Working Capital Management: There Goes the Rigor Evolutions in Treasury Centralization Distributor Finance: A New Strategy to Support Top-Line Growth and Sales into Emerging Markets