One and done?
"Doc, I (we) tried that once before and it didn't work"
For me, that's one of those "if I had a nickel for every time I heard that... I'd be rich" sayings.
When working with patients and parents of children with diabetes, I'm constantly attempting to explain, teach, or suggest the adoption of new ideas, devices, or strategies based on my interpretation of what I'm told by them or what I deduce during the encounter.