With last snapshot, you can now have this.
2020-07-07 to 2020-07-17 are closed
2020-07-13 is open
2020-07-14 is open for [Prototype design]
2020-07-2 to 2020-07-4 are closed for [Prototype design]
Project starts the 2020-07-01
[Prototype design] lasts 10 days
Then [Test prototype] lasts 10 days
[Foo] lasts 10 days
Are you expecting something like this?
We did not implement it for weekday but we can if this is useful for you.