How often is safe?

I have no reliable sources from medical professionals, but I don't think it would be unsafe to use it every day. However, I do think that the sessions are more enjoyable if they're spaced out a bit. I feel that the body is a bit less responsive to the pleasure if I do it too often. Maybe you could try leaving a day or two between sessions, and see if you notice any difference?

Had anyone read reliable (not just an opinion) information about how often is safe to do prostate massage.

I have not read or heard about any scientific studies regarding the health effects of frequent prostate massage. Just as there are very few, if any, scientific studies about erotic prostate massage in general, almost all we know is derived from anecdotal reporting such as exists on this Forum. About all I can point you to are the two user Polls -> How frequently do you use your massager? & How long is just right to ride your Aneros? for guidance. As you have noted, the information that does exist is pretty much just opinion but the preponderance of opinions seems to suggest that daily use is too frequent. Unfortunately, it would take a number of more detailed questions to ascertain the reasons for mens' individual choices regarding frequency of use. Wouldn't it be nice if some University launched a research project to study these issues? After all the Aneros Forum has a membership of more than 50,000 men, that is certainly a statistically significant number from which to draw some conclusions.
Good Vibes to You !

@Charlie1 Using the same reasoning as not looking at the clock during a session, I would let your body tell YOU how often it wants a session. Lately, I have been having almost daily sessions now for a week. Is that too much? Not for the way I am feeling! If you don't have any negative factors after frequent sessions (soreness, etc.) then go for it!

Yes @goldenboy couldn't be more right on this: let your body tell you what's up. If you want a session every day, try it! If one of those sessions seems to be uncomfortable, then you'll know that maybe 4 straight days is too much but 3 straight days of sessions is ok. Pay attention to how long your sessions last too. If you feel like you're "done" at 30 minutes but keep it in for another 30 minutes, and you try that every day and you wind up with discomfort, then scale back the amount of time each session until your body is used to it.

You might find that you have the drive (the sex drive, that is) to have a session every day. But just don't over do it! Waiting between sessions can ramp up sexual desire and over all make you more horny, which can lead to a better session. But I find that if I have a session one day and try again the next day that second session is way better than the one before it. My ass is already "warmed up" so to speak, and I just felt the pleasures the day before, so when I feel it again the next day, it's really good. It's like my ass gets more hungry for toys once its had a taste! I guess you should just go with your gut on this one. If for some reason you feel discomfort after or during a session, its not going to be the end of the world. You won't be damaging something or hurting yourself permanently, you'll just have some discomfort. And then you can try again! Whatever you do have fun 🙂

I would say your body decides how often is okay. If I'm sore or the muscles are tired I skip that day.