There is a difference between “planning it to run for months” and “placing the order for months of advertising in advance”.
Having worked in broadcasting, I can confidently say it is common for an ad buy to be modified multiple times during its run.
And the advertiser often doesn’t order the entire run up-front. They will schedule it a week or 2 at a time and adjust based on what results they are seeing.
There is a difference between “planning it to run for months” and “placing the order for months of advertising in advance”.
Having worked in broadcasting, I can confidently say it is common for an ad buy to be modified multiple times during its run.
And the advertiser often doesn’t order the entire run up-front. They will schedule it a week or 2 at a time and adjust based on what results they are seeing.