Bulk responding (select all and apply response)

Use case

I'm tasked with finding days when 25 staff available for off-site in 2024 (9-12 months away). There are 121 options across the 4 months, so it would be great to be able to 'fill all' days with 'Yes' (for example), and then set a few of them to 'No', if busy. Rather than making 100+ clicks.

Related, but not sure what a good UI would be:

If you could choose a default response for days that are given no response option (i.e left blank). Currently the default when leaving blank is 'No'. But if you could set this to 'Yes' — then responding to the above use case would simply be a matter of setting a few days to 'No' and then submitting.