Excellent point on research. A current project I’m working on includes a “overflow menu”.
We created a few versions of the navigation: 2 without and 1 with the overflow menu. We preformed several usability tests on each menu to see how intuitive each menu was.
1. How fast it took to complete a task of which required going into the “overflow menu” on one navigation while the other two had the options right on the screen.
2. Number of Errors made when trying to performed the task.
3. Satisfaction. On a scale of 1–5 how would they rate the experience.
The results were inconclusive. Each menu had similar results.
We opted to keep the overflow menu for the first release. As we start to collect analytics and the site evolves the overflow menu may go away.
I think the main takeaway I got from this article is the OVERUSE part. It’s not all or nothing here. It’s a great reminder to be intentional with the design decisions we’re making. But I gotta say, there’s a lot of “more” menus out there in the wild, see some examples here: https://medium.com/bread-crumbs/does-website-navigation-want-more-more-more-3889bece4287#.4lufjm7rx