I tried this out for our situation... it was right on for child care and food (low cost plan) but way high for rent (mortgage), healthcare, and transportation. Their "utilities" bucket was also very broad and covers:
Utilities, fuels and public services
Household operations
Housekeeping supplies
Household furnishings and equipment
Furniture
Floor coverings
Major appliances
Small appliances, miscellaneous housewares
Miscellaneous household equipment
which they estimated we should be spending $24K /year on (!!!!!). No freaking way. We spend about half that for a 7 person family that lives (in my view) in the lap of luxury itself.
It's an interesting tool, but so much is discretionary.