often in a team with backend developers, frontenders ad/or designers working with core and contrib finding and appling patches managing configuration preparing the site for other user roles on the production site
content and users changing UI text: in blocks, messages, automated emails adding or disabling menu items disabling blocks adding forms without constant access to a sitebuilder or themer
I need how often where to understand the concept once on help page and online documentation as a reminder a few times on admin pages to choose the right tickbox, field, format etc when I use it labels and field help