Early in life your usually not making the $$ to save an extra 10%. Until I was in my early 30's I didn't have enough extra to buy a new lawn mower. I'm at 52, have a decent amount saved but I wonder if it's enough. The SS and US debt is going to blow up about the time I should be getting medicare/SS. So you have to plan for that, plus healthcare cost is going to eat my generation up.
My - I'm pretty well fugged math
If I retire early, we need $2500 month healthcare minimum (insurance, meds, co-pays, etc).
Property tax/ insurance/house maintenance $1000
transportation $600 (tires, new car, oil, etc)
Food misc - 1000.
Beer, blow, and a can of alpo prime cuts $1000
So - early retirement is expensive - like ~$6k a month minimum net after taxes. That's having your house and stuff paid for. So it's a good thought but you really need 6-8k a month gross income to do it. And that's a number that needs adjusted for inflation.
SS starts to run dry in 2034, or 15 years. So the real answer is you won't really know if an extra 10% will be enough. Especially with the rise of socialism and communism in this country, they will try and raise taxes to 50%-70% because giving your money to someone else is what they do.
The US federal debt is at $223k per person and rising. We have hit the point of no return. So assuming things will stay as they are now is probably a bad bet.