Here's what I do: I have 5 different worksheets set up in my template file each worksheet with a different series of details (ie for different construction types). I keep these updated as I keep my template updated (if I create a new detail on a proect I copy it into my template for future use). On each sheet I have up to about 15 details drawn into frames that I have sized to fit 4 to a sheet on my layout and I just resize the layout drawing as required for the details I want on my layout. This means I can customize details on the fly if needed for an individual project and I don't have to have multiple files open and be cutting and pasting etc.
I don't like the idea of using module files because if you update the source file then the target module in a drawing file can update and then you have a slightly different set of drawings to what was issued to your client.
I also don't like the idea of using external drawings from another pln file. What happens if your folder tree structure changes down the track? Will the link be lost and also what if you want to customise the detail later.
I think its better to keep everythng in one file.
V12-V27, PC: Ryzen 9 3950X, 64g RAM, RTX5000, Win 11