Option Greeks are metrics. Some option strategies are developed to be managed using Greeks, and some are not. The usefulness will depend on precisely what you are attempting to accomplish. Some strategies that ARE managed by Greeks, may focus on a subset of them only, which is a function of the strategy again. Use of the Greeks can span a very wide range of complexity. Managing by the Greeks typically infer holding multiple legged option positions. -- This can be a very deep subject. ;-)