I have never bothered with the fuel containers as they emptied out from use. I use it until the container is almost empty. I then dispose of the small amount left and refill the container. I also empty the airplane's fuel tank back into the container when I am done flying that plane too. I have never had a problem with the fuel so far.

I think the problem is not having a good container that is sealed up Ok so it doesn't leak or allow it to breathe (as the temperature changes the air is drawn in when cold and pushed out when hot). Also my containers are sealed all the time. I have seen folks leave their fuel container open at the flying field for hours like that, and then they complain about how the fuel goes bad so fast on them.

I have had problems with those plastic jugs leaking in the past, especially from the bottom, so I use the metal gallon containers for my flight box fuel container.