I rest my fully extended bow hand index finger along the shaft while I draw, and I know I'm at my 27.5" draw when my finger feels the tip of that insert. At that point, I lock in my back tension and continue my shot cycle. Obviously, this requires me to shoot 30" arrows but it works out well for me because longer arrow reduces my gap and confirms I'm hitting the same draw length every time. Like everything else in this sport, it's all personal and different for each one of us... It may help u. I hated the idea of using a clicker so I made a mental one out of finger lol