I've used templates for sites for years, and loved them, BUT been frustrated at the redundant effort involved in setting up and maintaining the pages. Changing the navigation when it's embedded in every page, or adding an ad banner, so many little changes require editing every file. Not my cup of tea... so I wrote a tool to split web site template themes apart from the content.
I've used this for years now and love it. Saved me hundreds if not thousands of hours.
What I do is use ".HT" files. .HT is a file type that combines the template at run time, like a CMS would do, but without any hooks inside the content pages. None. They're 100% unique page content. It 's sort of like how a .css file moves styles to one place -- but this does it for the template's HTML.
This link--
How to Use .HT Files
-- details what I did and how you can do it too. Hope you find it useful!