Link delay in calendar days, not in working days

No, delay is alway in "open days"

Do you have an idea about doing that in a better way so that the next activity move automatically ?

As of today, there is no way to do this.
Delays are always in open days.
What you want would need an evolution. Two possibilities :
- New planning mode "fixed calendar duration" (similar to "fixed duration" but in calendar days, not working days)
- Possibility to define that delays on dependencies are in "calendar day" instead of "working days" (new checkbox in the definition of dependency)
Possbily both evolutions could be done.

I recorded both as Tickets #3318 and #3319
Sure this evolution will have very low priority in our roadmap.

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