A 10b5-1 plan is not mandatory. It just serves as an affirmative defense against insider trading. And there are no limits as to when a 10b5-1 plan can be enacted, as long as the officers are not in possession of material information at the time of enactment. But the SEC was investigating those plans a few years ago because they had a very high "abnormal" return rate and were "well-timed" according to their investigation.

An officer can sell their shares on the open public market based on information that has already made public by the company. If he is aware of material information that has not yet been made public and acts upon that information, that is illegal insider trading.

Obviously if insider transactions were not a big deal Wall Street would not place such a large emphasis on insider activity.

Speaking of a 10b5-1 plan, Doug Parker exercised his Stock Appreciation Rights as laid out in the plan. They would expire worthless had he not exercised them.