Reserve Fuel

I have a question about the reserve fuel on my 14 Kodiak. On mine I have to turn fuel selector from Off to On to Reserve. I know gas goes bad after awhile,, so my question is how does a person use the Reserve fuel before it goes bad? I have figured to just turn it to Reserve and drive it, and maybe hopefully as it goes down the new fuel in the main tank will mix with it and keep it kinda fresh.

Any ideas will be appreciated.

Thanks