1 - I hold as long as necessary to make an accurate shot. No use wasting lead downrange because I hurried the trigger pull. At the same time, I train to reduce my "on target to trigger pull" time to under 5 seconds. I simply want to be as quick to make the accurate shot as possible. But I don't want to rush the shot and take a chance on a miss or a poorly placed shot. 2 - To focus my parallax I range the target then place the parallax dial on the appropriate setting. That's it! I don't mess with the diopter at all after I've locked it in during my rifle zeroing. I look through the reticle to the target and try to intuitively see the reticle cross hairs and intended POI as a single object. A basic marksmanship rule of thumb is "don't shoot at something you can't see". I agree with the previous comment that you need to look at that target. Just like practicing dry fire technique in your living room. I like to practice "seeing" various targets around my property. That helps me get used to putting the rifle into a good shooting position, as well as getting good practice at repeatedly looking through the scope and being satisfied with the sight picture I have acquired. If I'm not satisfied with my "dry fire" sight picture, that is the time to analyze any changed to the parallax setting or diopter setting that will make that sight picture clearer. That way I'm not messing with anything in the field in order to get a crisp, clear sight picture.