No, it is not required to create tabs for campaigns that don't require any bid modifiers.
It is hard to delete a tab, and then bring it back later, so if you want to temporarily disable a setting, you can pause it by using the Paused Tab.
If bid modifier is updated for the "All campaigns", then the script will modify all the campaigns. If you'd like to apply bid modification to only a few campaigns, then create one tab per campaign. Paused tabs, in this case, will be entirely ignored.
There is no way to mix and match 'all campaigns' and single campaigns. The bid modifiers mentioned in the spreadsheet reflects the target bid adjustment so the script doesn't stack bid changes.
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