then I just copy what I need over so all the details are just on one worksheet in the project.

I'm similar to Arcadia's system is I have worksheets filled with clusters of details. Still have to load the parts into the project though. I also use it as a viewer for my libraries so I don't have to have the project folders loaded up with unnecessary libraries. Even if it just a couple of small changes, because then it becomes kind of a history that has its own benefits for little over head. And when I make something new in the project, I just copy and paste it back to the storage project so I can keep it for future use. When I go to do details or add any 2d work, I just copy and paste what I need over so my project files don't get choked up. It's layer list is standardized for this office so I can copy and paste to and from my projects easily. I kept an extra instance of Archicad open that has all of my libraries, notes, and details.

Other's may think their own system is better than mine but that's the beauty of Archicad - you can skin cats in many different ways:) I'm sure you will come up with a system that works for you. Better to have all details within your project file. Some like having details externally that are linked but this creates problems as if you update your external std it will update in your project as well which can cause inconsistencies especially if you need to customize something. If I want to customize a detail I just use the detail tool then copy and past into it from a base standard detail or I just amend the standard on my details worksheet. All these details are on the template already so when I create a new job I can delete the worksheets that contain certain detail classes (ie for construction types) that I know I wont need then I'm left with just one detail worksheet placed with multiple instances on the layout for as many std details as I need. I drop the whole worksheet onto my layout as many times as I need and re-size it to the appropriate grid square for the detail I want on the worksheet. Personally I have sets of std details drawn in a grid pattern on several worksheets. There are quite a few different ways that people do this.

Archicad 16 detail library