I sometimes buy minilab chemicals and share them with other amateuer photographers (as part of a buying group). The shelf life of virgin cans is at least two years if stored properly. I would expect that a full bottle of devided concentrate lasts as long, but I use them up before. The major advantage of minilab chemistry is that you can keep it in the tank of a roller transport machine until it gets too dirty. It will degenerate as fast as single-use chemicals, but can be refreshed by adding a small quantity of replenisher prior to the next use. However, you may also use this minilab chemistry one time without replenisher (e.g. in a rotary tube) and it is still more economic than amateuer/prof. chemistry