Bruce, because I was spending most of my time in Turkey and only visiting the UK twice a year (last 4-5 years) my Replenished Xtol would sit idle for months in storage. I ran test films through before using and found no differences after a year in storage I would previously have been turning over a 5 litre batch split 50:50 stock and repleniosher in under a year, more like 6 months often continuing replenishment with another pack of Xtol for up to 2 years before starting afresh.