Hi Dave,
"Fixed crawl" has been around quite awhile but is more popular on other sites. It's basically addressing the string 1/2- 1" below the nock in order for you to reduce your "point on distance" to normal hunting ranges of 20-25 yds. This allows you to basically put the tip of the arrow on the vital center at any range you'd shoot a deer and be confident of having a lethal double lung hit. That part is irrelevant for what I'm talking about, but this is accomplished by raising the shaft to where it is directly under your eye, which should, at least theoretically allow you to gauge the trajectory of the arrow better relating to obstacles it must clear. Basically, it's roughly equivalent to sighting down a slug gun vent rib. I generally agree with Jason that it's best avoided, but in this case I did have a slight angle facing away where I thought I could get top of one lung/ bottom of the other and the heart if I didn't. It just that when one shoots gap the gap looks a whole lot different in the horizontal plain than the vertical, when the tip will generally be at the deer's hooves (roughly 18-20" below the spot. In hindsight, I should have just Geronimo'd out of the tree and broke the deer's back and probably my neck!