The central question for governments and central banks is when they withdraw the many life-support packages they have given banks during the crisis. For the European Central Bank’s covered bond programme, that time may be approaching.

The ECB has now spent almost a third of the 60 billion euros set aside for covered bonds, a form of secured debt issued by banks that plays a vital role in funding Europe’s mortgage markets. With the covered bond market up and running the programme is starting to look redundant.

Bankers praise the programme as a roaring success. Sales of the securities have picked up since it was announced in May, and the risk premium investors demand to buy the bonds has, on average, narrowed by over two thirds. Less well-established issuers in Ireland, Greece and Italy have managed to tap the market. Even UK banks, whose bonds aren’t on the ECB’s shopping list, have benefited from the broader recovery.

How much of this is due to the covered bond purchases is hard to gauge. At just under 20 billion euros, the purchases are just a fraction of the overall liquidity the central bank has showered on the market. The revival may owe as much to the overall improvement in the credit markets — helped by central bank interventions — than it does to the specific covered bond programme.

However, bankers say the ECB’s buying acts as a psychological support for the market. Investors are more confident buying the debt because they know Frankfurt will step in if conditions sour.

This is a good reason for the ECB to keep the programme open. However, the central bank should slow its purchases.

So far the ECB has bought steadily, even during quieter months. At its current rate it will have spent half of the cash earmarked for covered bonds by January.

But banks that sold shorter-dated two-year notes in 2008 will have to refinance next year. If the recovery stalls, bond markets may also lose some of their froth, which would push up banks’ funding costs. By reining in purchases now, the ECB would have dry powder to use next year, if the need arises.

At some point the market will need to stand on its own feet, without the psychological crutch provided by the ECB. Slowing down purchases now shouldn’t drive up funding costs or shut issuers out of the market. But it would give the market the chance to prove it doesn’t need Frankfurt’s help.

That may be an even bigger psychological boost.