What you're describing applies to coffee shops where a latte has the same amount of coffee regardless of the cup size.

Others are mostly describing someone who makes coffee for themself at home or in a break room. That person likely chooses a cup size depending on how much they coffee they want, how frequently they want a refill, etc.

you're partially right. It doesn't matter if they had specified the grams of coffee beans they used to produce those cups. It would have been better to specify both number of cups and how they were produced.

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