4:49 : If you steal gas, you don't want to finish it as a will need 2 marines to kills it if you keep stoping it and rebuilding it. And the don't want to make another marine since he is making reactored hellions.
I think the only time the terran will make only a single marine is if you go gas first reactor hellion, which you can't even really afford to expand very fast behind. You always get at least 2 marines, and then either make a third or wait for 50 gas to tick over.
I think iaguz makes the third marine there, and I've fallen in love with doing it as with 3 marines you can push out and easily clean up 4 lings... on big maps you will often even deny drone scouting, so just seeing 3 marines pushing out and deny lings seeing the reactor/factory can throw zergs off.
kinda off-topic with regards to ZvT, but there should always be more than one marine out there.
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