As a best practice, where would a form that is used in multiple programs be...

A form that is used in multiple programs should be stored in the Design Studio as a global asset12. This allows the form to be easily reused and updated across different landing pages and programs without creating duplicates or inconsistencies3.

A form that is stored in Marketing Activities as a local asset is only available within the specific program where it was created1. This means that if the form needs to be used in another program, it has to be cloned or recreated, which can lead to data quality issues and maintenance challenges3.

There is no such thing as a global asset in Marketing Activities. All assets in Marketing Activities are local to their respective programs1. References:

1: How to create and edit forms | Adobe Marketo Engage

2: Marketo Success Series: Forms - Marketing Nation

3: Marketo Form Best Practices - Marketing Rockstar Guides