@Jody ********
I have a couple people who work offshore on that 28 on 28 off rotation. Two of them were raked over the coals by immigration officers when they stamped in, cautioned to get real visas etc, and told they can't get in any more on 30 day visa exempt entries :O The other one who works with them has never been asked and comes and goes every other month for years and years.
I have no idea how they decide who they are going to target.,.. It doesn't make any sense to me.