“A critic looking at these tightly focused, targeted interventions might dismiss them as Band-Aid solutions. But that phrase should not be considered a term of disparagement. The Band-Aid is an inexpensive, convenient, and remarkably versatile solution to an astonishing array of problems. In their history, Band-Aids have probably allowed millions of people to keep working or playing tennis or cooking or walking when they would otherwise have had to stop. The Band-Aid solution is actually the best kind of solution because it involves solving a problem with the minimum amount of effort and time and cost.”