A company's strategy evolves from one version to the next

because an ongoing tide of new and stricter government regulations forces managers to make strategy changes in order for the company to remain in compliance with shifting regulatory requirements. because ongoing pressures from shareholders for higher profits and bigger dividends force top management to institute new and bold strategic initiatives of varying kinds to produce better overall company performance.

as managers abandon obsolete or ineffective strategy elements, settle upon a set of proactive strategy elements, and then$--$as new circumstances unfold$--$make adaptive strategic adjustments, all of which result in an assortment of reactive strategy elements.

because of ongoing turnover in the managerial and executive ranks $($new managers often decide to shift to a different strategy$).$

because of shifting managerial conclusions about which strategy alternative is actually best.