I am Right Eye Dominant and for quite a while my left eye tried to take over the aming. Every time that happened, I missed the target all together. What I did to defeat this tendency was to squint down or close my left eye all together.

Another thing that was hard to learn to get lined up correctly then IGNORE the No-Peep. This too can create a lot of problems.

The bad thng is that out of a dozen target arrows I only have six left [and I never lost an arrow] that missed because of the left eye problem. The six were shot through or bent in the fletching area when hit with another arrow.