Best Practice for Templating-Workflow, coming from static HTML I hope this question does not sound to banal:
I am currently switching to Craft CMS and I am used to build my HTML/CSS/JS templates as static pages with dummy content. 

This (seemingly?) has 3 advantages for me:


I have an early, clickable prototype, presentable to the client
before I have to touch any CMS
I am not forced to insert real content via the CMS yet 
It gives me a very clean Git Repository for the frontend without any
CMS dependencies yet


The disadvantage is of course that I have to manually split my static pages up later to work with Craft CMS (or any other CMS) templating logic.

Thus I was wondering how you approach templating, especially with Craft: Whether you start directly building your frontend from scratch in Craft’s Templates folder or if you start independently, and do the splitting of files every time as a necessary step …

Any suggestions?
We used to do what you are doing, for a good many years - it was especially helpful when we didn't know what CMS we were going to use yet, or when we had a front end specialist (hello) who would send the files off to the back end specialist for implementation.

However, with Craft, we've found that the front-end people can use it well enough to not need a 'back end specialist', so we find ourselves no longer doing site builds as front-end assets first. It's just faster and easier to build the HTML/CSS/JS from inside the Craft templates.

We also used to (and still do for larger projects) build a completely non-styled "blueprint" of the website. The objective was to ensure that the site structure was correct - here's an example: http://example.bp.myvcsite.com/

That was/is part of our whole approach where we split things into blueprint; visuals; static build; CMS integration: http://example.myvcsite.com/