The saying is true, and a group like Broadcom illustrates it well, even if its astonishing expansion and excellent profitability owe as much to the quality of its management as to the fair winds that have sustained its activity.

Just look at the network equipment manufacturer's track record over the last decade, which has seen a tenfold increase in sales and a thirtyfold increase in free cash flow.

This performance is largely due to its very aggressive acquisition strategy: net of asset disposals, the latter has swallowed up $45 billion over ten years, or three-quarters of the Group's profits.

As it has also returned exactly the same amount to shareholders through dividends and share buy-backs, the $30 billion "hole" has had to be filled by a comparable increase in debt.

The latter remains sustainable, but cannot be pushed to a higher level. It's a safe bet, therefore, that management over the next decade will be less aggressive than over the last.

At the end of the cycle, Broadcom shares are trading at x25 cash earnings. Yesterday, the group published good annual results, but they show that, excluding acquisitions, its growth rate is much more modest.

So it's hard to get enthusiastic about its current valuation multiples.