Activity durations are normally estimated in an intuitive and subjective way.

 Activity Duration Estimation Techniques:

Accurate estimation methods include detailed breakdowns, using experienced personnel, and analyzing specific factors for individual activities.

Relying on gross estimates or averages (as in A) introduces significant inaccuracies.

 PSP Study Guide References:

The PSP Study Guide emphasizes the importance of detailed and specific input to improve estimation accuracy​.

 Analysis for Selection:

Option A: Incorrect method, as averages do not provide accurate results for individual activities.

Option B: Misguided suggestion; focusing independently on activities without logic paths introduces potential errors.

Option C: Correct. Dividing activities enhances detail and estimation precision.

Option D: Correct. Involving the executors ensures realistic and experienced-based durations.

 Conclusion: The correct answer is A, as using gross estimates is not an effective method for improving accuracy.