Oooh this is a goodie.
Previously I have been doing this via two separate goals, one for drinks per week (do less) and one for days_per_week_with_zero_drinks (do more) and needless to say it is annoying and confusing.
How do you do your data entry? Do you enter the triangle numbers yourself into Beeminder?
EDIT: The more I think about this the more I like it, because it actually encourages you to drink less per sitting. My days_per_week_with_zero_drinks goal actually encourages binge drinking provided there’s enough credits on the other goal (and they derail independently so the math gets hard).