Those numbers are published by people who make money selling investments. To reach 100% of income you would need to save 25 times your salary given a 4% safe withdrawal rate that ensures you will not run out of money. Possible, but not realistic for most people.
People who have actually retired on
www.retireearlyhomepage.com and message boards report they actually spend about 35% of their old salary. This assumes you have paid off you mortgage and have no debt.
Salary-income taxes-SS taxes-retirement savings-mortgage-debt payments-college & other savings etc = about 35% of gross income. I know this is true in my case. On a 100k income I spend about $3k per month after savings and mortgage interest.
The big variable is health care, but if I was retired and had more time I could probably cut my current expenses 10-15% by smarter shopping and that would help cover some of it. Worst case Social Security is projected at 70% of my promised benefit and that would also help. Could also take a reverse mortgage if that was needed.
My personal goal is to shoot for 50%. I think saving 12.5 times my salary is realistic and is a good balance that will allow me to retire at 60 if I choose.