When we first started tobi we had a pari proneb and pari neb cup. It took 35-40 minutes. A relative gave us an older devilbiss that her daughter used to use for asthma and noticed the tobi only took 20-25 minutes. I ordered a devilbiss pulmoaide that night online. I also notice if DS plugs his nose and uses the mouth piece it doesn't take as long, passive breathing will take longer, too.