How are you all doing light ice?

So I just got word that someone I work with just adds a little bit more than standard. We said that was not how it is and that you go a size above and for a trenta you fill a Venti the drink portion with one part of the drink and the ice the 2nd part of the drink. But in the cards you go to the juice line and then half way up the ice. How are all of you doing it? Are we wrong?