Had you adhered to the old adage "sell in May and go away" for the past three years, you would have not only avoided a lot pain, but you would have likely outperformed the benchmarks, as well. This as the springs of 2010, 2011 and 2012 each marked the starting point for sell-offs that would shave anywhere from 9% to 19% off of the S&P 500 (^GSPC) in just a matter of months.

In the case of Jeff Hirsch, the editor-in-chief at the Stock Trader's Almanac, it's not just about going away from the stock market, he says investors need to have a strategy that will carry them through until the fall.

"When you come around to the end of the best six months, e.g. April, and the market is up as it is, we start to get defensive," Hirsch says in the attached video. By putting what he calls "the prevent-D on the field," he implements a host of portfolio changes, such as tightening up stop-loss levels to bring them closer to the appreciated value of assets; limiting the new purchase of positions; undergoing simple profit-taking in winners and culling losers; and looking for possible short ideas and some asset shifting into bonds.

Historically, since the 1950s, Hirsch says the longer-term "sell in May" results are also compelling, but never more so than in the past three years. In 2010, for example, the high watermark set in late April did not get permanently eclipsed until December — and then, only by about 3%. In 2011, the high of the year was hit on May 2 after the S&P 500 had gained 9%. But over the next five months, stocks fell 20% and would ultimately finish the year flat, which was still 8% below where they were eight months before. And then again, in 2012, a searing hot first quarter saw a high set in April, followed by a sell-off and five unproductive months while the market got back to even.

"Bull markets don't go wrinkle free," says Hugh Johnson, chairman & CIO of Hugh Johnson Advisors. "They get a bit overvalued and a little undervalued. Right now, if anything, we're a little overvalued."

Not wanting his observation to be construed as a trading call, Johnson says no one has a timing edge, even if they claim otherwise. The prudent thing to do as he sees it isn't to jump in or out of stocks entirely, but simply to "drag your feet when it comes to making new commitments to the equity markets."

While not a trader per se Johnson does have his timing "tells," one of which is to take money off the table when a stock or sector's price starts to lag that of the market as a whole. Trim a little to stay ahead of a real pull back that tends to shake investors out at the lows.

On a 5 to 8% pullback, Johnson is a huge buyer. He sees no evidence whatsoever that the bull cycle is coming to an end (fits and starts on the economy aside).

Johnson's biggest contrarian play is a whopper.