I keep ten or twelve gallons of gas at any one time in the basement garage. Storage is in the red plastic type gasoline containers. I never smell fumes from them.
I started using Sta-bil last year after having trouble getting one of the quads to fire up in the spring. The Sta-bil bottle claims to allow gasoline to last for 12 months, doubling the life of it. So I take that to mean gasoline lasts 6 months. It seems to work well with my mixed fuel too.
Since using this stuff both quads easily fire up everytime. It is now in all the fuel in all my yard equipment. I used the chainsaw for the first time in a long time the last two weekends and it fired right up. So I am thinking the Sta-bil is good stuff.
If I put on my tin foil hat I can easily imagine that the .gov is pleased fuel does not last very long in storage. When the S does HTF they don't want us serfs being mobile.