Janet Yellen is arguably the most powerful woman in the world. Her leadership style can be summed up in one word: cautious.

Since she became head of America's central bank, the Federal Reserve, in February 2014, the world has braced for interest rate increases.

So far, only one has come.

"My position has been, and remains, cautiously optimistic," Yellen said in a big speech Monday on the state of the U.S. economy.

Experts wonder if Yellen is too cautious. Two-thirds of the economists surveyed by CNNMoney this week believe Yellen is dallying too much on raising rates. They point out that the U.S. is near full employment and continues to grow.

"It seems like she's waiting to get everything pointing in one direction when she moves rates," says Maury Harris, chief U.S. economist at UBS. That just doesn't happen in the real world. He believes it was a mistake not to raise rates last September or even earlier this year.

Related: Will the Fed raise rates before the election?

The Fed is on hold (again)

Whether you agree with Yellen or not, what we've learned in nearly 2.5 years of her tenure is that when there is any doubt, the Yellen Fed goes on hold. Understanding her cautious approach is likely the biggest clue to predicting where the Fed is headed.

So a rate hike in June looks off the table after lousy hiring in May. The rest of 2016 is in doubt, too. There's less than a 50% probability that the Fed will raise rates before the U.S. presidential election, according to the CME FedWatch tool.

The go slow Yellen Fed wants to avoid raising rates too fast that it spooks markets or causes a recession. But being so hesitant to act is beginning to cause other problems.

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The Fed's new problems

1. Credibility. Yellen is fond of using the word "gradual" to describe her approach to rate hikes. But is six months (or more) between rate hikes gradual? Waiting so long calls into question whether the U.S. economy is really strong enough for rate increases or not.

"It seems like they get very caught up in short-run developments and aren't looking at the bigger picture," says Harris at UBS.

2. Confusion. Yellen and other members of the Fed are giving a lot more speeches than any in the past. The idea is to increase transparency, but so much talking can backfire as members seemingly contradict each other.

"She's almost painstaking about trying to communicate her views, even though the market is confused by them," says Kristina Hooper, U.S. investment strategist at Allianz Global Investors.

3. Unprepared for next recession. A deeper concern is that the Fed is tip toeing so much on rate hikes that it will leave America -- and the world -- in a very bad position when the next recession hits. The push to avoid a recession now could backfire when the downturn comes, as it always does.

The typical response to a crisis is for the Fed to cut rates by 400 basis points. At the moment, the Fed fund rates is sitting at a range of 25 to 50 points. There just isn't much to cut, leading some to say the Fed (among other central banks) has run out of ammo.

Economic forecaster James Smith of Parsec Financial is one of many who told CNNMoney that he just doesn't understand what "possible harm" a 25 basis point increase would do right now.

Related: Yellen reels back Fed rate hike talk after 'disappointing' jobs report

Yellen is in uncharted territory

Yellen has stressed repeatedly that her Fed team is "data dependent." They don't have a pre-set course in mind for rates.

In the past, the Fed has typically raised rates in a series of steady moves in one direction. But these aren't normal times. The world is still trying to get back to full strength after the Great Recession. Even the U.S., which is fairing better than most major economies, continues to be viewed as B+ strength.

Some economists think Yellen is right to be cautious given the unprecedented situation the world is in.

Related: The U.S. is 'basically at full employment'

"We're in uncharted territory...this is a Fed that really is being more thoughtful," says Hooper. She thinks the Fed made the right call to pause earlier this year after the stock market tanked on fears of a major China slowdown.

Yellen is the most powerful woman in the world because her words and decisions reverberate around the world.

"This is almost the equivalent of holding the nuclear suitcase as president," says Hooper.

The curse of being Fed chair is that mistakes aren't clear until the the next recession hits. Just ask Alan Greenspan.