This feature was widely used by our clients. When we launched our navigation builder in 2012, we provided our clients an option of utilizing content regions of varying sizes. Each dropdown menu then would properly lay itself out based on whether it had content in both main region columns, content in just one of the main columns, or no content at all.
In addition, we offered several settings that toggled behaviors such as distributed items, equal-width items, left-and-right floated items, and more. It also had a migration mode, in which clients and designers could preview their new navigation while still showing end users the old version, which was based off an include file.