From progress override to Retained logic in an updated schedule

“What is the difference between Retained Logic & Override Logic?” is a frequently asked interview question. Usually, people answer this question by saying the definition of each term. But what is the actual difference and when can we use each of them or change the scheduling options from one to the other. This article will highlight the differences, when to use each, and finally changing from one to the other.

Defining retained logic and progress override

Retained logic: An activity starting before its time neglecting its relations. The remaining duration of the out-of-sequence activity will be scheduled to start only after the predecessor activity is scheduled to finish.

Progress override: disregarding the relationship between activities and schedules any remaining duration of the “out of sequence” activity from the data date. In other words, P6 allows the out-of-sequence activity to proceed without waiting for its predecessor to finish, starting from the data date.

Usually, when asked this question in interviews people define them as terms and say they prefer the retained logic to respect the relationships created. But sometimes the relationships are already ignored as per the progress. You can read more about planning interview questions here.

For example. You planned to finish all the masonry works on the first floor and then start the plaster. You finished 50% of the masonry activity and the plastering team finished the ground floor instead of wasting resources you decided to start the plastering process on the first floor for the 50% masonry that was finished. Here, in this case, you did not respect the relationship you created. So, scheduling using retained logic is no longer accurate.

You will continue the plastering work; it will always be a smaller percentage than the masonry activity, but it will not stop as the retained logic will assume.

Meanwhile, the progress override will ignore the relationship and assume that plastering and masonry will end together in this case without stopping the plaster until the masonry is completed. As per the below screenshot, the forecast finish date of the plaster is almost the same date of finishing the masonry which is not logical, so if you are going to use progress override, use it with caution!

Converting the schedule from progress override to retained logic

If you received or started working on an updated schedule that was using the progress override and for some reason you want to change the scheduling options to retained logic. You have several steps you need to make to avoid any unaccepted/illogical schedule.

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1-Adjust durations and relationships to finish at the finish date required with no negative float.

2-Adjust durations and relationships to finish at the finish date required with no negative float.

Fixing the out-of-sequence

Fixing the out-of-sequence will be the first step after converting from progress override to retained logic. The out-of-sequence is any activity that is in progress or has been completed before one or more of its predecessors.

We have several cases:

1-If the relation between two activities is FS and the successor is completed before the predecessor and the predecessor did not start. We can fix this case by deleting the relation since it was not a mandatory relation.

2-If the relation between two activities is FS and both the successor and predecessor are in progress. We can fix this by changing the relationship type from FS to SS.

3-If the relation between two activities is FS and the successor is in progress while the predecessor has not started yet. If it is a mandatory relationship, you could break the successor into two activities. One that was completed and link it to a finished activity and a remaining activity and link it to the not completed predecessor since both will not be in progress.

4-If the relation between two activities is FS and the predecessor is still in progress while the successor is completed. You could break the predecessor into two activities. One that was completed and link it to the remaining of the same activity and link the remaining part to another not started activity.

Let us place it in a tabular form to make it easier to implement:

Using Excel to solve the Out-of-sequence

You can export from Primavera P6 the relationships between activities and filter using the activity status as mentioned in the points above.

Here we changed the relationship to SS between the predecessor and successor in one step using Excel.

After finishing, make sure that you solved all the out-of-sequence activities by checking the log.

Your log should be like this the out-of-sequence should equal zero.

Adjust durations and relationships to finish at the finish date required with no negative float.

After finishing the out-of-sequence you should go back and check the durations and relationships to make sure you are finishing on the required finish date with no negative float.

Conclusion

Understanding the differences between “Retained Logic” and “Progress Override” in Primavera P6 is essential for efficient project scheduling. “Retained Logic” guarantees commitment to network logic, even if it causes delays, whereas “Progress Override” allows for greater flexibility in scheduling, potentially accelerating project progress. The choice between these options should line up with project objectives and the impact on timelines and resources.

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