While I doubt that this technique actually works on fouled spark plugs (although it might be worth a try, haha), sometimes problems actually do solve themselves when you do nothing. That approach works particularly well with other peoples’ problems that they want your help with. About 80% of the time, when you tell them “I’m busy right now, but I’ll help you tomorrow,” the problem will already be solved by the time you call them on the next day.
As with all things in life, the trick is to distinguish the situations where the wait-and-see approach is appropriate from those where it’s actually detrimental, such as e.g. medical problems or when your engine is on fire.
Does anybody have a great story or example of a self-solving problem?