Here's my method... WARNING - paleolithic process will be described!
I have PLN files for 'storage' of details, based on types. I have a PLN for standard door / window details, structural, pools, wall assemblies, stairs / rails, etc.
Each of the PLN files have stories established for subdivisions of types and scales. For instance, my standard door / window detail file has a story for each different window manufacturer. My structural file has stories for foundations, floors, roofs, steel connections, concrete structure, etc. I use the stories as an organizational tool (that's the critical concept).
All my details are simple 2D drawings. They're drawn inside standard size boxes, or multiples of standard boxes. The PLN's are all scrupulously maintained to reflect the latest office standard as far as layer names, fill definitions, fonts types and sizes, etc. They only use four layers... one layer for linework and fills, one for annotation, one for dimensions and another for identification (titles, etc). These layers correspond to my 2D layers used in my model view sections, so that if I have my 'SECTIONS' layer combination turned on, my details are turned 'on', too.
To use the details contained in the 'storage' PLN's, I open the PLN that contains the details I want and copy them. I then go back to my project file and paste them in (see below for where they go). There, I make any job specific edits. Since I've been careful to maintain drafting standards in the external detail PLN's, the pasted details fit seamlessly into my project file's 'system' without adding extraneous layers, fill types, pens, etc.
Now to the using them in the project file...
I set up a story for each different scale of details involved in the project (In reality, these stories are part of my standard template). I've got a pre-defined 'grid' on each of these stories that gives me a full sheet of details for each of the detail stories defined in my template, along with a text label for me to fill in the sheet number it will occur on in my layout book. I paste the standard details into that grid. The detail stories are saved as views in the navigator, and are placed into my layouts like any other view in the project. If I have several sheets of details of a particular scale, I'll have several grids side-by-side in my model view and will adjust my drawing frame in the layout view to show each sheet on it's respective sheet in the layout book.
To create new or job specific details, I use the section tool to cut a section where I want to pull a detail, open it, copy the contents then paste it into the plan view on the detail story of the appropriate scale. I then edit or trace the resulting 2D entities to show what I want, how I want, and will frequently borrow pieces of my already-placed standard details to facilitate that. I take that result, move it into a box of the grid, and there it is.
I number my details individually. For instance, detail '1' only occurs ONCE in the finished drawing set, no matter what sheet it's on. On big jobs with lots of detailing the detail numbers can go into triple digits. Sheet AD1 will contain details 1 thru 15, AD2 16 thru 30, AD3 31 thru 45, etc. If I have details sprinkled throughout the set, this still holds true. Often, in that case, I'll skip several numbers to leave 'space' in the system in case I need to add another full sheet of details. The key here is to never duplicate a detail number... even if I were to screw up and have the wrong sheet number in a detail bubble, the user of the drawings could still rifle through the drawings and find that detail number on the 'wrong' sheet and it would still be the correct detail. I explain that to the builder at our 'kick off' meeting for the job.
The upshot is this... My details become a part of the project they belong to with no external references of any kind. If I were to transport the PLN file, it would have all it's data in that single file without trying to call any Xrefs or Modules from elsewhere on the disk. One of the problems with standard details is that they evolve... and I want that evolution to stop once they become part of an actual project... especially in the case where I've had to tweak them to fit specific requirements for a particular job.
Hope that makes sense... I wish i could =show= you how I do it... it would be much easier than describing it!
Still - if this interests you, and you need clarification, chime in and I'll provide further description.