I agree to a point with the above but there can be some fine tuning of the peep after you get the sights close.Most of us circle our housing so if we end up moving the housing after we had our peep set,we may find a slight peep adjustment is needed for maximum accuracy and comfort.
This is one reason I tie my peeps in,in such a way I can move them up and down without reserving.
It is also commom to set peep sights in for the kind of shooting you will be doing.For hunting you might make the peep most comfortable for hunting distances,like 25 yards.BUT,if you are a serious 3-d competitor,you might set the peep to be most comfortable at the average shot distance,for me I set mine at 33 yards(because my housing moved on a slider).If you were shooting 70 meters,you would set it for that.