Can confirm it's segments that matters. The "round trips" is to try and provide more familiar language to travelers as you said. To your example, long as the flight number changes between each leg, that would be 8 segments. Did 20 segments last year to get my status this way. (5 which were in a rt to BET and 4 on a rt to SJC)

Edit: I bring up the flight number because the milk run counts as one segment for miles and segments since it's all one flight number.