I’m currently working on a project where I’m using Pandoc which allows me to write and outline in Markdown with embedded LaTeX when necessary. When I have a new “style” I want to apply - indexable category, figures and summary information, etc. - I create a new macro and use that inline. My particular project has a lot of repeating elements, imagine a review of all Chevrolet’s, so one section has a significant number of pages that follow a similar structure - a table of common details, an image, a review.
So far, it’s working for me. Along with GNU make, Inkscape (for turning SVG to PDF), I’ve been happy with what I have with minimal embedded layout.