I first started using page-layout software in 1985 with Aldus PageMaker 1.0. If I recall correctly, it took a few years before you could create a master template that had items that appeared on every page, including guides that helped with placement of text and items.
With that historical perspective in mind, it's odd that while Pages 8 for macOS has master pages, it lacks a way to create non-printable master guides that appear on layout pages. There’s a way to simulate this effectively, although it triggers a bug in Pages that one hopes Apple will fix in a future release. (Master pages appeared as early as 2005 in Pages, but overhauled the whole iWork suite in 2013. I’m not sure how far back this bug dates.)
