torah study - What level of understanding is required in "learning" for purposes of making a siyum?

When learning as part of a coordinated group siyum, what level of understanding of the material is expected/required? How do you know if you've done enough to fulfill the mitzvah? Is it about effort expended, or about reaching a certain level of accomplishment (e.g. that you could pass some sort of test on the content)? How does somebody who is not already extremely learned (like, say, a ba'al t'shuvah), but who wants to help, know if his efforts will be useful?

This answer addresses learning in English rather than Aramaic and says it's more than just reading the words, which makes sense to me, but that doesn't actually say what level of proficiency one should be able to demonstrate.