Is it possible to nebulize too much hypertonic saline?

Not exactly answering your question but I don't think you need to be concerned about rebound nor tolerance with hypertonic saline. You can always cut down and see how you do.

I agree with scoop. In the talks on hypertonic saline, I haven't heard the docs mentioned that.

One concern might be for people with hypertension or heart disease who might need to watch their blood pressure and monitor for signs of fluid retention like swollen ankles or shortness of breath, especially with lying flat. Just a thought.

It's generally okay to use hypertonic saline twice a day, especially when you're feeling well. The goal is to keep your airways hydrated and clear, which helps prevent infections. You can always adjust your routine based on how you feel.
It is very individual, so you just pay attention to your body.

If you ever feel too much chest tightness or coughing that is not productive, or a lot of irritation in your lungs, those could be signs that it's too much.
But even if that happens, you can talk to your doctor about maybe using your bronchodilator first, just to open up the airways a bit.

I'm not having any chest tightness or irritation. No sore throat or coughing, other than the initial coughs with my first couple inhalations from the eRapid.

I have no bronchiectasis specialist where I live, unfortunately. The pulmonary specialist I was assigned monitors granulomas and nodules, which I also have (and am not particularly worried about). She warned me not to do nasal lavage more than a couple times a day; "God gives us mucus for a reason," she said. She knows little about bronchiectasis, and hadn't even heard of an Aerobika before. While she approves of me nebbing 7% saline 2x daily, it's something I learned from forums, not from her.

I feel like I got so "clean" yesterday I might be encouraging my lungs to make more mucus. Like...dried myself out a bit. Am I thus stimulating my lungs to make even more mucus to make up for the loss? I have no idea, and I expect my specialist has even less of an idea because this really isn't her department.

For a while, though, I'm going to see how I feel just nebbing once a day with the eRapid instead of twice, unless I feel some congestion.

@bronchiectasaurus I think you ask good questions. There is still a lot unknown about inhaled saline and airway clearance. I think someone just posted on an ongoing study being done on the impacts of inhaled saline on NTM infections. We definitely need more data. There are many different opinions and everyone seems to be guessing. As a result, for now, there seems no real basis for any hard and fast rules. I encourage you to experiment and find what works best for you.

After listening to my saga of how long I take to clear my airways, my pulmonologist suggested I set a timer for a certain amount of time and not exceed it. I've haven't done that as I seem to get interrupted here and there, but I have concentrated on decreasing my active huff coughing time. I'd be happy if I could get the routine done in 30 minutes (including neb time). I have not figured out if this is realistic yet!