While it applies to all design, not just landscape architecture, aligned elements are perceived to be more closely related than unaligned elements. This applies to elements either near or far.
This may be referenced as the continuous line theory of design or simply as continuity.
A bed line interrupted by a driveway that visually connects across the driveway is said to be continued. That’s an element that is aligned or continued effectively. It is the same for a point of focus perfectly centered on an opening or view such as a fountain or piece of statuary that is a continuation for the eye.
Continuous lines in landscape design are part of good design. They are both part of focus and part of transition. If a patio, deck and lawn are not logically connected they will be disjointed to both the eye and in practical use.
Aligning features and elements provides continuity and makes design more easily interpreted as well as more functional in daily usage.