dot and dab is usually pretty uniform (ie if i find a dot then i can assume they'll be in line?)
Not in my experience. It all depends on who put it up. Often it is job given to a knuckle dragging labourer because it's messy and no skilled labour wants to do it. You may be able to find where the dots are by knocking on the plasterboard - if it's hollow sounding there will be a void behind it. In reality often the only real way to find out is to cross fingers and hope for the best.
Not in my experience. It all depends on who put it up. Often it is job given to a knuckle dragging labourer because it's messy and no skilled labour wants to do it. You may be able to find where the dots are by knocking on the plasterboard - if it's hollow sounding there will be a void behind it. In reality often the only real way to find out is to cross fingers and hope for the best.