Based on the Critical Path Method, the last task in a project is always critical.
However, practically we know that the day when the project is going to be completed is never really critical. Instead, we care about Go live, Release, Practical Completion, ect. date.
This specific the CPM method may cause the incorrect calculations of Total Float.
Example:
Assume the deadline for 'Go live' milestone is 20 days after the current forecast. The schedule has one "Post Go Live' activity (without a deadline date) after the Milestone.
Practically TOTAL FLOAT for the 'Go live' milestone is 20 days. However, ALL CPM tools show that Total Float (Total Slack) = ZERO.
Even if the last activity has a deadline that is after the forecast date, the deadline will be ignored and TF will not that activities have Float.
It is a methodological gap :(
When the CPM method was invented, no one used it for the whole project. It just wasn't possible due to the limited power of the computers. So, the gap wasn't critical at that time.
Technically, it is a correct calculation, but practically, the TF Metric could be misleading.
