You should test ... test ... test it with many combination of Off Hrs as well as with those Holidays.
After that, You could know - do it works as it should work.
There would be some more features, which would help You.
It's You - who knows - what do You need more or something different?
> Sheets are protected that there could use only needed things.
As above test ... test ... test.
You do not need password now.
Good notice ...
I've not tested everything after any modification.
I added [ Edit Names ] -button as below snapshot.
Click it to change 'mode' ... if backcolor is green then can do selection otherwise could modify eg names.
There could be more ... something like this.