New file, adding resources changes duration, why?

[Milind]

Hello
In a new file, with 40 tasks, total duration shown is 30.48 days. However,
when I add resources to a task, the figure changes to 30.35. The task is of
2 days, time based, to be finished in two days with two resources, why the
change in duration? Even if I remove the check mark or put it again on
Effort based, still the duration changes.
Milind

 

[WSH]

I had that problem too ages ago. Its to do with the Calender! Make sure that
each resources calender add up the same working hours as the calender in that
project (Tools>Options>Calender)

 

[Jan De Messemaeker]

Hi,

Resource working toimes are different from Project calendar working times.
HTH

 

[John Sitka]

Make sure that

each resources calender add up the same working hours as the calender in that
project

Close but not quite. To assure NO change in total duration the various calendars would have to be identical.
Your project duration (sum of assignment durations) may straddle non working time of resources or tasks in an offset or stagger.
So a resource calendar working time that adds up (over a day, a week, a month ) to value X is not the same thing as a Project
calendar that adds up to value X over a similar time segment unless that time segment is explicitly defined
to the minute.

But the real point is you either want the duration to change or you don't. If your goal is to not have the duration
change then you make the assumption that you have infinite resource capacity and that eveybody can get everything
done by declaration rather than actually doing work. Impart that idea on real humans and they will push back.