I don't use the Library and only use LR for processing because I like the UI and the extras that ACR doesn't have. My workflow is to browse my hard drive with Faststone viewer - free and powerful - and when I see an image I like I highlight it and press E on my keyboard. All of the contents of the folder is imported but only the one I want is ticked and this is imported and the rest aren't and then I enhance it and save or import to PS. Now some will say I am ignoring the main part of LR but in all honesty life is too short to catalogue all of my images.
I'd say that life's too short not to catalogue one's images.
But since you clarified that and than said keywording, I'd have to both agree and disagree.
Adding keywords can indeed be time consuming, but nowhere near as time consuming as dealing with images that are not keyworded.
I think the secret is not to be too anal about keywording. Just add main keywords en masse to folders [can be done on import] and specifics to a few sub groups if need be. So on a day trip with girlfriend to the town of New Mills, everything gets imported with keywords New Mills, Peak District and then if I feel like it I may label a few sub groups with things like Millennial Bridge, river or Cows for pasture shots. Also I can take a shot at each location with my iPhone and then find shots in the map module as I can sync location info too.
Work stuff gets dealt with in the same way - client + job are the main keywords for each shoot then further keywording for specific stuff. I so wished I'd had a LR style organising when I used to do film stills.
The beauty of LR is that I can quickly keyword and then set up smart folders to pick up shots with say specific actors, locations or scenes even if shot at very different times. File Browser organisers like Bridge [which I was a big fan of until LR overtook it] are simply no match for the speed of such a way of working.