I cannot think of milestones without thinking of Miles Davis. In 1959 with Kind of Blue, a studio album from the Miles Davis sextet (pianists Bill Evans and Wynton Kelly, drummer Jimmy Cobb, bassist Paul Chambers, and saxophonists John Coltrane and Julian "Cannonball" Adderley), Davis moved from hard bop (jazz improvisations based on chords) to modality (improvisation based on a scale and creating melodies within the scale).
Kind of Blue arguably is the best-selling jazz record of all time and has been critically acclaimed as well as cited by composers of all genres as one of the most influential albums of all time. Roughly a year before Kind of Blue, Davis recorded (with a quintet since Bill Evans joined the group just before Kind of Blue) an album called Milestones. (To listen click Milestones.) That album featured modal experimentations which led to the establishment of the concept of modality in Kind of Blue.
Davis could not have changed and thereby progressed as a jazz artist without going through a transition. What is true for artists is also true for businesses. In the aptly named Milestones album Davis is experimenting, developing, and preparing for a change. Change is essential for successful businesses - it must be envisioned with planning, identified with a goal, and accomplished by the reaching of milestones along the way. Change is not instituted the way an on-off switch is toggled. The process of change is accomplished through transition from one milestone to the next, a logical sequence of steps, each anticipated and monitored as part of progressing to the identified goal.
