Some of it depends on where you live. We in Cali get a special gas that is even more prone to turning to crap that most the rest of the US. I don't leave gas in any of my bikes for more than a week without letting the carbs run dry. It's not going to be bad in a week, but if I forget about it, I know I am safe. Anything more than a month I use Stabil in it.
You could save yourself some trouble and use race gas.
My race quads start on the first kick every time, but I expect that from 110 octane leaded race fuel.