I agree with this. And this is why I plan to continue to w*rk a few hours a weeks after I FIRE this year (my own buffers then will be to maintain a SWR < 4, keep my savings in CDs and bonds, and w*rk a few part time hours).
Right now "one more year" still makes a significant difference, but at some point we'll have a larger portfolio with fewer years to make it last and more money -- then "one more year" will make relatively little difference