In the wild, when one animal is feeling stressed by the presence of another animal it has the option of escaping that stress by crawling away and finding a location where it can be alone. Not so in your current setup.
Ball pythons, like many animals, have dominant/subordinate relationships when they encounter each other ... this is most obvious in male combat during breeding season but plays out in much more subtle ways in female to female relationships and even male to female relationships whenever they encounter each other. The subordinate animals are always under some degree of stress from the presence of an "alpha" or dominate animal. How that stress effects the subordinate animal really depends on the individual.
Stress is bad for ball pythons ... even worse for gravid females ... and the crummy thing about stress is that most of the time you can't see it, smell it, or know it's there one way or the other until it's usually too late ... seems to me, it's better for the animals to take the possibility of stress out of the equation as best as we can. Housing each animal individually guarantees that stress from a dominant cage mate will not be a problem.
If you feel like your current setup is something that works for you, great! ... Just sharing my thoughts on the subject for whatever they're worth.
Blessings,
-adam