Practice shooting the EO-Tech with both eyes open. The EO-Tech and most other red dot type optics only reach their full potential when used with both eyes...Just check to insure that the eye you are using for the sight is your 'dominant' eye..
Dot Optics are designed, primarily, for Close Quarter Combat and 1 MOAs have a functional limitation of about 125yds, depending on the dot size.. Handgun dot optics usually have a 4 MOA dot and are limited to about 40yds...
I use one when I think my most likely shots will be within the 100yd range, if I think it will likely be farther I switch over to a 2-7x red dot scope.. both units have
Quick Detach mounts, so it only takes about 20-30 seconds and I don't have to worry about my 'zero'.
As far as shot placement, that can only be determined by your ability and the amount of solid practice you can put yourself through. In competitions, I've hit bowling pins at 100yds using my EO-Tech, but they were not the majority of my targets (nor did I usually get them on the first shot), or I would have switched over to the scope..The rest of them were in the 15-45yd range and it was not a real problem...