Just make sure that the client understands the concept that this new thing is for layouts that will be use on multiple pages of a site. I once did this and the person entering the content created every layout as a global layout and then used nothing but global layouts when creating pages. It was a nightmare and the need to query 6 to 10 other posts to display each page seriously dragged down the performance of the site.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users