Strategy formulation is

a$.$ static over time unless a newly appointed CEO decides to take the company in a new direction with a new strategy.

b$.$ developed solely on the fly because managers must make constant efforts to come up with fresh moves to keep a company's product offering clearly set apart from the product offerings of rival firms.

$$ c$.$ mostly hidden to outside view and is deliberately kept under wraps by top$-$level managers $($so as to catch rival companies by surprise when the strategy is launched$).$

$$ d$.$ typically planned well in advance and usually deviates little from the planned set of actions and business approaches because of the risks of making on$-$the$-$spot changes.

$$ e$.$ typically a blend of proactive and reactive strategy elements.