The way I do it is get the stave floor tillered to the point of where I could low brace it,then Ill temper,correct,and shape all at once....that way I only need to get the gun out once and your corrections will stay better being tempered in...I see lots of Guys having to get the heat out waaaaay too many times ....
And where the heck did you hear tempered hhb will take lots of set? A properly designed and tempered hhb for your intended weight and draw will be anything but set stricken...and if the stave has a medium to high crown on its back then trapping isn't nessicary ...i find just tempering,designing right,and tillering it well alone is good enough for the wood to get good results