The whole catalog - session thing can get confusing. I use Session for everything I do. They are easy when on location to work with and on coming home move over to the server. That being said I do create catalogs for each year. After I am done with the session, for the most part, I import it into a yearly catalog. This makes it easy with the use of filters, etc to say find all the images shot with the 100-400mm Sony GM lens or on a particular camera. It also allows me to take my catalogs with me if I am looking for an image or want to work with an image while traveling. If I use the catalog then I drag it over the existing catalog at it replaces the one on the server.
I also create catalogs based on events or locations. For example, I visit Antarctica, Iceland, Greenland Grand Canyon etc on a yearly or somewhat regular basis. So, for sake of example I go to Antarctica in November. At some point, I'll import the most recent trip to Antarctica into the catalog I have of previous Antarctica sessions. This allows me to go to one place to view all my images from certain trips. I also do that for family events like holidays.
In the past, I have had catalog issues. These seem to have gotten better in the last year but I would have catalogs that didn't upgrade properly and became unusable. I then had to go back and recreate the whole catalog.
Just my 2 cents.