It is possible to calculate the weekdays within a date range using formulas like the ones here:
and I can imagine that it would be possible to create formulas that would do the reverse, namely calculate a range based on including a certain number of weekdays.
However, I think it would be very tricky to calculate a range that takes into account vacations and public holdiays, since I imagine that this would require an iterative calculation.
For example, if a task is to start on Monday the 16th January, it’s no problem to work out that 15 weekdays would require 19 days in total (to accommodate 2 weekends) taking the task to Friday the 3rd Feb.
However, imagine if there are vacation days on the 20th Jan and 6th-8th Feb. It’s pretty hard to work out the end date in one simple formula. The 20th is in the middle of the initial calculated range, implying that the task needs to be pushed one weekday later. But this takes the task to Monday the 6th Feb, which means it actually needs to finish on the 9th Feb.
This results in recalculation and is likely to trigger loop detection and cause the formula to be disabled.
If anyone in the community has any bright ideas for how to address this, I look forward to hearing them