What do you want to achieve, how and why are all key considerations relative to getting things done.  When managing or leading others ( or even just yourself) the priority you assign to the objective versus how and why can vary.

Often those with a reputation for getting things done focus on the actual deliverable.  The reasons for doing the work are not considered important and the approach is not standard, that is, just something that works.

Sustainability

The direct approach focusing on outcomes can be very effective relative to achieving results.  The downside is sustainability.  In cases where the outcomes are not just one time, lack of sustainability can be an issue.

Many studies have shown consistent implementation processes coupled with a strong understanding of why things are being done result in more durable results.

Strategy vs. Tactics

How and why are the basic building blocks of a strategy.  Of course the goals are paramount but without supporting rational and underlying approach to achieve the objectives, it is not a strategy.

Tactically clearly defining what to do without reference to why, how or specific goals can work very efficiently.  It is a bit tricky to intergrate with other work and measuring is largely based on doing what you said you would do.

For sustainable results starting with a strategy to guide your execution may take a little more effort up front but in the long run it will pay off