The 1.08...1.09 multiplier for your inseam to adjudge proper saddle placement given crank arm length and seat tube height is a practice that is derived from tests of riders who were properly ankling their pedals with toeclips and referenced in Sloane's "The Complete Book of Bicycling" in my case a 35 year old edition. According to Sloane a peak for power output occurred at that multiplier for the inseam. There were a number of other variables such as crank length and consequentially seat tube height that are a function of riding comfort and whether you are using an over-square frame, and it follows, then, the stem length and handlebar dimension became other variables to fit the fact that folks of one vertical dimension did not conform to cookie cutter expectations.
Harrison Lee
Stockton, 107 degrees in the shade, CA