The sweet spot is a place where a combination of factors results in a maximum response for a given amount of effort. In tennis, squash, racquetball, baseball, or cricket, a given swing will result in a more powerful hit if the ball strikes the racket or bat on the latter's sweet spot.

Sweet spot
Sweet Spot
Sweet spots in functional glycomics
Sweet Spot Beam Splitter for Separating Images
Searching for Medicine's Sweet Spot
Rediscovering the sweet spot in drug discovery
Exome sequencing: the sweet spot before whole genomes
Sweet Spot Unit For a Multi-User Display Device With an Expanded Viewing Zone
Finding the sweet spot: the role of nature and nurture in medicinal chemistry
Hitting the distributed computing sweet spot with TSpaces