OK some people may disagree with me here. Not facts just an observation. Im curious as to whether others find this.
Cracks are a very general guide to roasting. They give you a ball park when you first start out. However different roast profiles, equipment etc will result in the cracks coming earlier or later in comparison to the color of the beans.
a popper for example which usually gives a very fast roast will give you an early second crack and you may want to darken them a bit past this point. on the other hand a Gene Cafe that gives comparatively slower roasts will have a delayed second crack, particularly if you back the temp off after first crack. roasting past the first snaps of second give a roast that is two dark for my pallet.
So in general I think that flavor is determined more by color then by snaps.