It used to be different. At one time, I worked the scans over in Photoshop first, then moved the semi-finished images to Lightroom for captions, keywords and cataloging. My rational was - I like to do most of the major editing on the 16 bit TIFFs, but after the heavy lifting was done, I could reduce the file size to 8 bit TIFFs for storage in Lightroom. If I saved the original raw scans, it was outside of Lightroom, and could be archived on another disc, if necessary.
More recently I have started photographing my negatives, and the RAW files from my 16MP camera are smaller than the film scanner files. Now I import the RAW camera files directly into Lightroom, then Edit them in Photoshop for the inversion, contrast, cropping, local adjustments and dust removal. Back in Lightroom I do the final fine tuning, and cataloging. With this method, both the RAW file and the edited TIFF are cataloged in Lightroom, tho at the cost of storing duplicate files. When I "Edit in Photoshop" Lightroom creates a 16 bit TIFF, but after I am done editing I save that as an 8 bit TIFF.