So for confirmation after reading and rereading different posts correctly set sag should be 1/3 of suspension travel front and rear

So for most dyna fronts sag should be 1/3 of 127mm = 42.3mm - I have diferent shocks with 66mm of travel they are set at 22mm

My question i see most say to set at 32mm of sag - why this figure ???? why not the 42.3mm

i set'em up @ 20 m,m, with good oil

i use a single rate spring

20mm front sag ??