You could always eat at every restaurant, demand replacements for your food because of defects (which don't have to exist) to get MORE food, AND not tip. Quite a number of restaurants will offer free food if they think you're unhappy.

Or you could go to a fast food restaurant and always take extra condiments and napkins for home use.

Or you could keep a used and washed soda cup in a backpack and sneak free refills at a busy fast food restaurant.

In general, you can justify a truly enormous number of tempting things to yourself with "In this PARTICULAR case, it happens to be perfectly appropriate to do (insert any action which you wouldn't normally do.)" To the point where it is a well known trope and it also gets a reference in chapter 10 of Methods of Rationality.

"Amusing, but that was not your first fleeting thought before you substituted something safer, less damaging. No, what you remembered was how you considered lining up all the blood purists and guillotining them. And now you are telling yourself you were not serious, but you were. If you could do it this very moment and no one would ever know, you would. Or what you did this morning to Neville Longbottom, deep inside you knew that was wrong but you did it anyway because it was fun and you had a good excuse and you thought the Boy-Who-Lived could get away with it -"

That's unfair! Now you're just dragging up inner fears that aren't necessarily real! I worried that I might be thinking like that, but in the end I decided it would probably work to help Neville -

"That was, in fact, a rationalization. I know. I cannot know what the true outcome will be for Neville - but I know what was truly happening inside your head. The decisive pressure was that it was such a clever idea you couldn't stand not to do it, never mind Neville's terror."

The other problem is that there is a well known process for how discrete actions (Move hand to object, grasp, move hand up to slot, insert grasped object, turn grasped object for a discrete period of time based on audio cues, release grasped object.) becomes trained tasks (Start Car)

What I see as the problem is where you start by thinking to yourself on a somewhat regular basis "Yeah, I can allow explicit special cases as long as the harm to others is at this relatively low level." and then get to "I can do harm to others whenever appropriate as the harm to others is at this relatively low level." as the new normal followed by a new special case where the harm is just a little bit higher.

To sum up, it's not the individual discretionary steps that I would worry about (any individual discretionary step can frequently be justified) it's the training effects of putting them all together on a regular basis.

Note: Edited to fix formatting.