But in Lightroom, you have an option to work differently. Sure you can keep all of your files in a single catalog (like Bridge), but you also have the option to create multiple catalogs. One of the way I keep sane while trying to keep track of my (near as makes no difference( 40,000 images is to have multiple catalogs.
When I first started using Lightroom in August of 2007, it didn't really make a difference, because I only shot about 1000 photos that year. I shot a lot more in 2008, but it was still manageable. Nearing the end of 2009 (with 20,000+ images) I was beginning to be overrun with folders so I though it would be smart if I started a new catalog to keep things tidy.
It was at this point I decided to keep one Lightroom catalog per year. I didn't go back and separate 2007 and 2008 out because frankly I didn't shoot anything really worthwhile back then, but it made sense for the future. My catalogs are simply named Digital Library 09 and Digital Library 10. The reason I'm thinking of this right now should have become obvious by now, its almost time to start Digital Library 11. I'm not the most organized person under the best of conditions, but I can keep track what year I shot something in pretty easily in my head so this makes sense for me. Switching from Library to Library couldn't be easier:
Another way to do it is one catalog per job, the way Capture One software does it. I'm generally not a fan of that but I do have a big multi-day multi-car job for Toyota potentially coming up, so I plan on starting a separate catalog for that client, just so I can find everything quicker. I suppose at some point it would make sense to start a separate catalog for Message In A Bottle as well because soon that's going to run across multiple years.
Diving a little deeper into the catalog, you then have the option of naming your folders. Here are a few examples of naming conventions from my 2009 catalog:
As you can see, I store things by date, by location, sometimes by camera (although that can be sorted through metadata) by client and by subject. It may seem silly, but no single way seems to allow me to find files as easily. Anyway the point is, know all the options available and implement the ones that make sense to your workflow.