Every “just this once” is practice for the next once.

The phrase works by promising that the event is sealed off from everything around it. It never is, because you did not only take the shortcut, you also found out that you are a person who takes it when conditions are bad enough. The second time arrives with a precedent attached, and conditions never have to be as bad.

Notice the words when they appear, and treat them as the tell rather than the reason. Then do the small boring version of the right thing, which is four minutes of work. You are not deciding about today, you are deciding what will be easy in a month.