Can organizations over-plan? Why or why not?

Answer 1

as an ex-planner in a large organization [tens of thousands of employees], i say "yes".

No plan survives contact with reality. Thus, the effective purpose of planning is to:

a) decide what to begin now by having proposals compete for limited resources, and

b) determine your organization's capabilities and resources.

As soon as reality disrupts your plan, you'll have to scramble to make the right moves. At that point, knowing what resources you have and can divert is priceless.