"You cannot force what isn't there" - words from my crusty old pulmonologist over 6 years ago. Some people have "dry bronchiectasis" and produce very little mucus.

Early on in my MAC days, I tried to clear every last bit out of my lungs - ended up with sore ribs and throat. When I saw the RT, she explained that keeping everything moving is the point, not getting every drop out. She told me trying too hard can irritate the lungs and actually produce even more mucus. She recommended stopping "as soon as the flow slows down" but not doing the airway clearance any longer than 30 minutes.

These days I neb or exercise, use the Aerobika, then try huff coughing and deep breathing for 6-8 minutes. If nothing comes out by that point, it isn't going to. Sometimes, later in the day, I can feel stuff moving and do the breathing and coughing again to get a little out. This method has kept me healthy for almost 5 years.