I take HS 7% twice a day and sometimes 3x a day when I am coming down with something. Also if I do 2 vials a time it makes a big difference, but it is unfortunately not in my budget to do this. Of all the things I've inhaled, Pulmozyme, Tobi, Cayston, Hypertonic Saline is the only thing that has not given me bleeds.
Please note that the studies indicate that if you use 10ml. of 7% each time, you may have a 10% increase in lung function, so if you can do multiple vials at a time, and you have a good way to cover the cost, you'll get better results that way, then just sticking with 1 vial in the morning and another in the evening. You'll enjoy being "clearer" between treatments.