The internet tends to consolidate a lot of polarized experiences, so if you spend too much time on this forum you will begin to think that ball pythons never eat and constantly get RIs, haha. Truth is that while it is common, as already stated, good husbandry is crucial to keeping any sickness at bay.

Also, maintaining good hygiene when handling snakes foreign to your collection will drastically decrease the odds of your animals having an RI. If you go to expos, pet shops, or handle other people's reptiles, it is imperative that you disinfect your hands, and ideally change clothes before you come back to your collection. Quarantining new arrivals is also good practices. There is some debate as to how long to do this. Some say 3 months, others 1 month. Point is that some type of quarantine will lower your odds of disease transmission.

I also think that an overlooked factor in disease prevention is the health and packaging of feeder rodents. While freezing rodents does cut down on some bacteria, we know that many pathogenic strains can survive the freeze/thaw process. I have also found that some frozen feeders come packaged 'dirty' with spots of feces and other contaminants on them. While its hard to completely avoid any contamination, buying rodents from reputable sources will help keep your bp disease free.

If you maintain basic standards you should be fine. With enough snakes in a collection, you are bound to run into an RI once in a while, but being prepared, as it seems that you are, will make it a much better process.