In addition, John Lonski, chief economist at Moody's, said a gradual pace of tightening diminishes concerns that interest rates will suddenly shoot up and affect companies' ability to generate profits, whether through increased borrowing costs or decreased consumer spending.
Traders increasingly expect a rate hike as early as September. Whether that's a single, 25-basis-point increase or the start of a longer trend, the pace will likely differ from the last tightening cycle, which saw consecutive rate hikes for a total of a 425-basis-point increase between 2004 and 2006.
A "fast" cycle describe a series of hikes in successive central bank meetings, the Ned Davis study said. That quick pace is true for seven of the eight tightening cycles since 1967.
Fed talk points to a slow cycle this time. As Fed Chair Janet Yellen emphasizes, investors should focus on the pace and not the timing of rate hikes. Those remarks helped stocks rally slightly, as did lower median rate targets for 2016 and 2017 in the policymakers' "dot plot."
"The speed of interest rates increases matters," Clissold said. "During slower tightening cycles, investors have a chance to adjust to a rising interest rate environment. During faster cycles, investors may be behind the curve constantly."
But even after a six-year bull market, some strategists say the long-term outlook for the stock market remains bullish regardless of when or how quickly the Fed raises rates.
Read MoreCiti economist: Fed is too chicken to hike rates
"If you're a long-term investor you should look through (the rate hike)," said Robert Pavlik, chief market strategist at Boston Private Wealth. "That's how I'm advising people and handling my clients' money."