Hand-coded vs CMS

When I do web development most of the time I write every line myself and in cases such as slideshows, import and tinker with 3rd party code. I'm also fine with CMSs and have spent some (but minimal) time with Wordpress, Drupal and Joomla.

Clients want to be able to log in and update websites theirselves, which I think is great, and is usually when i'll go the CMS route. Please help me out with learning about other options that allow clients to do things themselves but let me code and understand the entire system. I swear I know the name of what I'm looking for but I can't remember it lol.

Are you talking about building a bespoke CMS? It's can be an absolute pain depending on the client but it will allow you to build as much or as little functionality as you want. They don't have to be complicated.

You could build a really basic one in less than a day that lets people login and (add,edit, delete) pages.