I laughed at myself when I saw I'd begun this thread.
The answer to my question is: yes. Those little wax potpourri cubes really do only last about 2 weeks in a "warmer". When one is accustomed to plug-ins that last 90 days or candles that provide a visual cue as to when the fragrance will end, the basis for comparison to the wax potpourri is a bit skewed.
I have moved from using petroleum wax candles scented with synthetic oils to soy wax candles scented with essential oils.
"Our past is a story existing only in our minds. Look, analyze, understand, and forgive. Then, as quickly as possible, chuck it." ~ Marianne Williamson