The old stock market adage goes, ‘sell in May and go away’.

In short, the thinking was that summer months were a quiet time in both the worlds of business and finance, so it made sense to sell down some shares in May, enjoy a long and relaxing summer, then come back to the market recharged in the autumn.

So, should I ignore my portfolio from the end of this week for a few months?

Yes, no, maybe…

There is actually some research into whether this strategy tends to outperform or underperform the market. As with many such areas, the results are mixed.

If one strategy is proven to deliver consistently strong results, it often attracts investors to use it, which in turn typically reduces its effectiveness.

Nonetheless, some studies have found the ‘sell in May’ approach can work. Others have reached a different conclusion.

Rather than get into the debate about specific months of the year, I want to zoom in on one element of the approach that I think can be helpful.

Constant activity adds costs

The idea of a long summer where months go by without even looking at the value of your ISA or SIPP may seem like something from an Enid Blyton book. But is it such a bad idea?

Research this year by AJ Bell suggests that women investors tend to trade less often than men, but with better results.

As a long-term investor, that makes sense to me. Jumping in and out of shares frequently is closer to trading than investing.

It can push up transaction costs, eating into returns. It also means that an investment case does not have the chance to prove itself over the long term.

As Warren Buffett’s partner Charlie Munger said, “the big money is not in the buying and the selling but in the waiting“.

Indeed, Buffett himself said that if someone was not willing to own a share for 10 years, they should not even consider owning it for 10 minutes.

My approach this summer

Looked at another way, that suggests one ideally ought to be able to own a share confidently without wasting the summer constantly checking its price.

Still, that does not mean I will go away from the market next month.

This summer, I will continue to hunt for what Buffett called great companies at attractive prices that I could imagine holding for a long time (Buffett’s favourite holding period is ”forever”).

For example, one share that I think is worth considering now for its long-term potential is FTSE 100 consumer goods maker Reckitt Benckiser (LSE: RKT).

The company’s portfolio of well-known household brands like Dettol gives it pricing power. Its global footprint helps the company benefit from economies of scale.

But the share price looked costly to me for years.

Down 30% over the past five years, though, the share price is now just 10 times earnings. Add a 4.6% yield into the mix and I think that looks attractive.

A disastrous past acquisition of an infant formula business continues to pose litigation risks. The Middle Eastern conflict threatens ingredient cost inflation, potentially eating into profit margins.

Looked at on the timeline of a decade not just a summer, though, Reckitt’s future looks promising to me.