Method When do you drink backup glass

[sifp]

I know you're supposed to have a backup glass of sn, but under what conditions do you take it? I know you're supposed to take it if you throw up, but how much puke triggers the backup protocol? Is there any reason not to chug the whole second cup even if you only throw up a little? The more the better right? What if you throw up the second cup? Third cup? Abort?