Getting the timing right in withdrawing additional liquidity is likely to be decisive in order to ensure a non-inflationary recovery. Generally speaking, the lower the reversibility of the nonconventional operations, the larger the risk of being behind the curve when the macroeconomic and financial market situation improves.
Indeed, to a large extent the speed of unwinding of unconventional measures would depend on their degree of reversibility. As I already noted, some of the unwinding would happen automatically as central bank programmes become increasingly unattractive as financial conditions normalise.