Currently, I am using SharePoint Designer to manage apps, edit HTML pages and manage files. I thought I would use it more to edit forms but I prefer InfoPath. I find it more useful to edit. When I want to get a clear picture of the hierarchy in SharePoint, I use SharePoint Designer. I find it difficult at times to navigate the breadcrumbs to get to what I want. It does not seem to be too forgiving when you want to navigate from one subsite to another.