Regarding the benzonatate...over the years and esp when I had the horrid cough prediagnosis, it was prescribed several times and was useless for me. I think it was because my cough was from excessive post nasal drip, which it doesn't help. Perhaps it helps with dry coughs.
It's not usually used for pneumonias or COPD exacerbations because we want patients to get secretions out of lungs.