And the benefits are enduring, rather than one-off.
Their role is to prevent one-off surges from translating into persistently higher pressure on prices.
Utilities are supposed to let you Build one-off applications cheaply and easily from the materials at hand.
But those feats probably speak more to the fact that, in a one-off game, tactical nous and individual exploits can subvert conventional wisdom.
Aggregate profits growth has been flattered by the performance of Wall Street firms and distorted by one-off changes in the accounting treatment of inventory profits and depreciation.
But any new rules, if not carefully formulated and, above all, enforced, could provide a one-off opportunity for mass expropriation.
"She wasn't going to be always doing some one-off trip because a Congressman needed to be stroked," says someone close to her, requesting anonymity to speak candidly.
"Selling Asia and Latin America would ruin the group's growth prospects, and would not benefit shareholders beyond the one-off cash payment," says Mr Suchet.
But the mammoth, although instantly recognisable, is drawn in a quite different way - simplified and schematised, somewhere between a caricature and an abstraction, and this is no one-off accident;
In 1998-99, this provided about 66 per cent of total revenue. The rest came from the Government's one-off grant, fees and charges, and rental income from market stalls, kiosks and restaurants.
At the last Paris show an experimental hybrid Jaguar was the star. At Geneva this week electricity even reached Rolls-Royce, with a one-off battery-electric Phantom on show.
