I think all these various calculators are fine to play with and I'm sure each one helps to answer some different nagging questions. But when it's all said and done, using such calculators is a bit like measuring with a micrometer and cutting with an ax. NOTHING w*rks out in retirement the way you plan or expect. BUT you CAN go into it with the knowledge that (barring the apocalypse) you have enough.
I did all the "readers digest" or similar magazine calculators over the years (worst thing about them was they asked YOU what rate of return you were going to get - ridiculous.)
When I found FIRECacl, I was pretty well done. It showed I was in good shape. I played with some variables and eventually pulled the plug with the expectation that I would do fine. I did.
Honestly, the best handy-dandy calculator I've seen is the "4% rule." Of course, it's a bit sloppy, and you have to make a couple of caveats (40/60 to 60/40.) Maybe be ready to cut back a skosh if things get tough. Other than that, most people are good to go. No fuss, no muss.
Having said that. I think a lot of people like the process of calculating every detail which gives them a better feeling that nothing has been left to chance. Of course, everything is left to chance since we're talking about the future.
I like your approach! Not yet retired yet, but all the calculators are pointing in the green zone. And if life has taught me anything, it's as you pretty much stated, nothing ever quite goes according to plan.
Having observed various family members in retirement, and having been privy to the financial pictures in case of parent/in-laws, there is clearly more than one way to approach.
My in-laws provide a great example: they were fiscally modest people that had a really really great lifestyle on a fraction of what I "think" I need, seasonally shuttling between their Northern home and waterfront warm weather condo, surrounded by friends and family in both. Never really needed to tap their nest egg owing to SS/pension income until the very end, and even then barely, granted that was a decade ago. Biggest financial worry was what to do with those pain in the a** RMD's.
Lessons I should learn from the examples (both positive and negative) of my in-laws and other family elders:
(1) You'll probably need waaaay way less than all the budgets and fancy calculator tell you you'll need.
(2) Chances favor you dying or becoming physically limited sooner rather than later than you think you will.
(3) Spend the money for travel and experiences sooner rather than later, cause either you won't be in good enough shape later, you won't feel like it later, or significant others won't be around to share it later.
(4) Keep your family close if you can - you'll need them, they'll need you too.
(5) Put a plan for medical decisions and end of life in place ASAP. Don't wait. Decide who you trust carefully on Healthcare Proxy, Power of Attorney, Executor, etc., make sure your wishes and priorities are well known by all relevant parties.
(6) Don't skimp on the professionals (fin'l advisor, lawyer, etc.) - use specialists not a generalists, you'll be doing yourself and your family a big favor.
I'm sure I'm missing plenty. YMMV.