The lead article conflates two process: habits and incentives. The very term "reinforcement" dates back to before the distinction was well-understood. Only in the last decade has it been known that habit operates from a neurology distinct from incentives. (The habit mechanism is in a much older part of the brain.) Only the first story, Yudkowsky and the jellybeans, deals clearly with reinforcement of habit. The others are probably primarily adjustment of incentives.

In using habit and incentive, different rules apply. Incentives require that the subject discern the contingency. The processes Skinner studied as "reinforcement" are mostly about incentives. You adjust schedules of reinforcement to alter the organism's expectancies. For incentive effects, consistent reinforcement is not usually best, as the results are subject to extinction soon after the organism stops getting the reward.

Habits, on the other hand, are blind. The organism doesn't need to see any contingency. Yudkowsky continued to be nice even after he no longer received the jellybeans. To form habits, as opposed to incentive structures, consistency is key.

In short, as a general rule, you want consistency to reward habits and considerable randomness to create lasting incentives.

But the difference extends also to the ethical questions raised. Altering others' incentives for our own benefit is part of ordinary human interaction. If his colleagues surreptitiously timed the offer of jellybeans to Yudkowsky when he acted nice, this is something else; the ethical reason is that Yudkowsky need not recognize what he's being rewarded for to be affected by the jellybeans.

Both habit and incentive are "powerful." But they're powerful for different reasons, in different ways; and to apply them effectively and ethically requires different procedures.