More on Chaos control.
The most dangerous outcome of the underplanning is employee frustration. Without clear day-to-day targets, employees loose interest in the work. Some become anxious, not willing to take on responsibilities beyond what they consider their assignment.
The danger of the overplanning is that detailed plans are hard to change.
The rigidness of the plan is proportional to the time spent on it, as the only reason not to change plans is often sheer inertia of those that invested already a lot of time to write it up, in the first place.
An ideal planning phase is short and concise, and the planing granularity is barely sufficient to distribute the day-to-day assignments to the employees.