Yes, your grammar is correct and you can say it without a time frame. Example: You sit with a friend for breakfast and he orders pancakes. You could easily ask How many of those things (referring to pancakes) do you eat? The same is true when referring to drinks.

If you say "How many of those things do you eat?" it is correct but it is not clear what is meant. This question needs to be time-bound like "how many of those things do you eat in a day?" "how many of those things do you eat for breakfast?", etc.