Activity duration estimating involves assessing the number of work periods likely to
be needed to complete each identified activity. The person or group on the project
team who is most familiar with the nature of a specific activity should make, or at
least approve, the estimate.
Estimating the number of work periods required to complete an activity will often require consideration of elapsed time as well. For example, if “concrete curing”
will require four days of elapsed time, it may require from two to four work periods
based on (a) which day of the week it begins on and (b) whether or not weekend
days are treated as work periods. Most computerized scheduling software will handle this problem automatically.
Overall project duration may also be estimated using the tools and techniques
presented here, but it is more properly calculated as the output of schedule development (described in Section 6.4).