A session is of course different from a "peformance" in my book at least.
Whenever any starts one of these threads about "performance", I automatically assume a stage, an audience and payment for one's efforts. If that is what Guest Ian has in mind, then the zero-zero option is the only sensible choice.
If however, it is a pub-based free for all, then by all means drink as much as you want. Everybody else will be pissed as well.