If you’ve set up multiple availabilities in NeetoCal and want to block a specific time across all of them, instead of making the changes in the availability overrides in all the availabilities, the easiest way is to mark yourself unavailable in your calendar.
NeetoCal automatically syncs with your calendar and respects any event where you are marked as Busy. This ensures you're shown as unavailable during those times across all scheduling links that rely on your connected availabilities.
This is the example for Google Calendar, but same would be applicable in Outlook and iCloud.
Open your Google Calendar.
Click Create to add a new event.
Set the date and time you want to block.
Make sure the "Busy" status is selected (do not set it as "Free").
Click Save.
Once saved, NeetoCal will detect the event and automatically block that time across all your connected availabilities.