I went to a deferred comp retirement planning meeting last week and was quietly laughing at the calculator tool examples of "typical expenses". Not only does it assume you still have a mortgage, but that you spend $250+ on household furnishings/supplies, $150/month on clothing, $730/mo on transportation, and over 500 on various "other" categories. I'm guessing the numbers are just the national US averages for such things, but it was nice to be able to just use what my wife and I already spend and mark N/A or 0 next to many.
The biggest IF boils down to healthcare for us, as my wife does have various conditions that add up and sadly we'll have to plan on a budget that assumes maxing out deductibles on any plan we get, so about 25-30% of our total retirement budget after copays and all that. We can retire at 50 thanks to our pensions and paying off the house by then (and selling it to buy a cheaper one and save the extra principle) but when her life literally depends on getting proper healthcare it makes that leap quite stressful.