If you are struggling with your holding time at anchor then you may consider your draw hand and how deep your hook is. Recently I thought that the early pre-load on my ACS was the reason for my holding woes. I even began to think I was over-bowed. Not so. When I stopped to look over my form in all the different facets I noticed my hook had become shallower than usual. I went back and shot a few arrows paying close attention to my deep hook,,, bingo. Everything was more relaxed now. Hold time increased and consistency picked right back up. I also picked up on a rising draw elbow,,, no detail too small to not be looked at.
With that said,,, be mindful of everything.