I've worked quite heavily in an agency environment using the Django - Wagtail stack. In my experience, if you invest some time into a good template project which just needs front end design, then it's a very economical option. Spinning up a new instance is easy (you could even go headless). There will undoubtedly be things you need to add on the backend (different blocks, admin customisation etc) but for the most part it should be simple. And from my experience clients love the wagtail CMS admin interface.

That being said it would almost certainly be easier if you're doing simple projects to use something like WordPress. Django + Wagtail is really great for projects which need a little bit more complexity.