My tongue in cheek unified theory of chickenheartness. With hindsight fairly on the mark though not precisely.
Placing a moistened finger on the belly button I thought how the past year went as to expenses both planned and unexpected, how Mr Market was doing and how I felt about it. A bad year had me pick a number below 4% and a good year ie low unexpected expenses and a performing stock market had me pick a higher number above 4% usually remodeling, a upgraded pickup truck and added travel. Note the emotion and after the fact re -planning.
Tried always to raise or lower budget expenses NOT asset allocation. Hand grenade wise pretty much stayed close to 60/40.
1993 - 2006 Would not look pretty spreadsheet wise because of a mish mash of severance pay cash, some temp work, sold a rental duplex, DRIP dividend stocks and things like Wellesley, REIT index, corporate high yield, etc letting the index funds compound in my 401k rollover from ER start age 49 1/2 to 62. Also took early small pension at 55 and SS at 62.
Messy but it worked. As forum members will attest there are many ways to skin a cat.
heh heh heh - now past 70 1/2 my Pals at the IRS help me with my withdrawal rate. Given the historical period 1993 -2015 and hindsight I was overly frugal in the early years of ER but I don't feel deprived or think I should have spent more when I was younger and more 'spry'.