Buy cheap, sell high. That is how the old saying goes. When it comes to investing, I am happy to buy at an attractive price, even if it is not necessarily cheap – and then hold for the long term. Over the past year, Shell (LSE: SHEL) shares have done well. They are up 36% — and 144% over five years.

So, might they still be attractively priced for a long-term investor like myself? Or could it make more sense to do nothing for now?

Strong business, helped by the oil price

The reason for that rise is not hard to discern.

With oil prices having soared lately, companies that extract and sell the black gold are in clover.

Indeed, while Shell’s 36% jump in the past year is impressive, rival BP has performed even better. Its share price is now 60% higher than it was 12 months ago.

It is possible to look at those sorts of price movements and put them to down to current high oil prices. If they come back down to earth – as they will sooner or later, based on historical norms – then both Shell and BP shares could fall.

But it is also possible to overstate the short-term factors here. Shell is a massive company with large reserves. Even if oil prices fall, it could potentially still generate chunky profits.

Even after its share price climb over the past year, the Shell dividend yield of 3.3% is slightly higher than the FTSE 100 average.

My concern about buying high

Still, while there is a lot to like about the Shell business, the current valuation does not strike me as particularly attractive.

Shell shares sell on a price-to-earnings ratio of 15. The prospective valuation could be cheaper, in fairness, as rising oil prices may help boost Shell earnings in coming quarters – perhaps substantially.

However, my approach to investing in cyclical industries like oil or mining is that it is best to try and buy at or near the bottom of the pricing cycle, when selling prices are depressed and share prices tend to be cheap too.

It is never possible to know with certainty when we are at the bottom of the pricing cycle. But I do know for sure that with oil prices where they are now, we are nowhere near it.

I could still buy Shell shares today, likely picking up some dividends along the way, and hang on while hopefully they go up in value.

But as a long-term investor, I am not simply seeking to make a fast buck. I want to buy at what I see is an attractive price and then hold for years, without worrying about short-term movements in the oil price.

On top of that, the last time I owned Shell shares I got a nasty surprise when – in 2020 – it cut its dividend for the first time since the Second World War. That is a risk with any share, but it did underline for me just how damaging an oil price crash can be for the company’s finances.

So, while oil prices remain elevated, I have no plans to buy Shell shares again. Fortunately, there are other shares in the London market that look like much better value to me right now.