Where I train, there's an hour long Saturday class. It's an hour long as opposed to the 45-minute or 90-minute classes we have during the week. I like Saturdays because:
-there's usually not a lot of people so there's no excuse to slack off - the instructor will see it if you are!
-I don't get as tired as I do in the 90-minute classes but I sweat more than I do in the 45-minute classes
-since there's fewer students, there's more time for individual instruction
-and, since it's at 1 pm, I can sleep in a bit first and then I have the rest of my day afterward!
Even though Randori night is my favorite, Saturdays are pretty awesome too.