There are some interesting theories based on seat allocation in planes that could be put to use here, and would allow the prisoners to get in and eating their meals a lot quicker than they currently do. There's a
pretty good article on it here with a bunch of cool computer models that demonstrate the different methods, from "sit wherever the hell you want" to "outside in" and even a kind of "staggered outside in".
In terms of prison canteen seat choices, I've always preferred the idea of having a rigid one in one out system where they're all in a line and get given their food at the end of the queue, but PA seems to prefer a more freeform method. As such, perhaps an initial seat-choice would be best, and then a calculation to determine where the closest food is to that seat. In your image, that would mean each canteen station would end up catering toward 48 prisoners at a time (which I imagine is how you designed it) and they would all just sit down next to it (which in practice means that they're not wasting 10-15 minutes of their eating time just trying to sit down). That being said, assuming that the prisoners don't talk to one another or have "designated" seats, you could end up with some awkward posturing when two prisoners pick the same seat and then get in a fight over who saw it first.
In all, I imagine we could probably get pretty deep in the logic of how to pick the best seat and end up with something ridiculous like
