Indexing databases is often thought of as an art where the database is the canvas and the indexes are the paints that come together to form a beautiful tapestry of storage and performance. A little color here, a little color there, and paintings will take shape. In much the same way, a clustered index on a table and then a few nonclustered indexes can result in screaming performance as beautiful as any masterpiece. Going a little too abstract or minimalist with your indexing might make you feel good, but the performance will let you know it isn’t too useful.
As colorful as this analogy is, there is more science ...