All the more reason to get organized for everybody's sake.
can't see a roster working for SL, there are over 10 girls any given day, some start at 9:30 some at 10:00 11:00 and noon and even afternoons, they can come and go as they need, its a good freedom for the Girls, so even if there was some sort of a roster it could change at a moments notice, a Client would still have to phone and make an appointment and ask for said Girl, well she is off today or starts later than you want to come.
If you are a regular at SL then you have adapted to their system, I know I have I either contact Tina prior and by prior I mean the night or two before I want to go and sometimes the morning of and it revolves now on Tina answering or texting back as she has a life too. or if I have the Girls number I set up with her, but I still give Tina a heads up message that I set up so she doesn't get double booked. I have never phoned the front desk nor have I just walked in, but I may try that cause I know all the Girls and wouldn't have a problem picking anyone of them except I might get some sad puppy dog eyes when trying to decide who to go with...haha