Strategic planning should be static or flexible ?

It should be both.

Static in terms of finacial expectations, core business, and holding strategic  market direction.

Flexible in design and implementing parts of strategy that are to do with people, marketing, product trials and customer perceptions.

Thanks for the invitation, I am not expert in this feild,

Strategic planning is flexible

full Defination of planning the act  or process of making  or carryingout plans,specifically.the establishment of goalspolicies and procedures for a social or economic unit.